Wikipedia:Manual of Style/Dates and numbers

"WP:NUMBERS" redirects here. For the Wikiproject, see Wikipedia:WikiProject Numbers. For the notability guideline, see Wikipedia:Notability (numbers).

This page guides the presentation of numbers, dates, times, measurements, currencies, coordinates, and similar material in articles. Its aim is to promote clarity and cohesion; this is especially important within an article. The goal is to make the whole encyclopedia easier and more intuitive to use.

Where this manual provides options, consistency should be maintained within an article unless there is a good reason to do otherwise. The Arbitration Committee has ruled that editors should not change an article from one guideline-defined style to another without a substantial reason unrelated to mere choice of style, and that revert-warring over optional styles is unacceptable. If discussion cannot determine which style to use in an article, defer to the style used by the first major contributor.

General notes

Quotations, titles, etc.

See also: WP:MOSQUOTE

Quotations, titles of books and articles, and similar "imported" text should be faithfully reproduced, even if they employ formats or units inconsistent with these guidelines or with other formats in the same article. If necessary, clarify via [bracketed interpolation], article text, or footnotes.

• It is acceptable to change other date formats in the same article to provide consistency, so long as those changes would otherwise be acceptable.

Non-breaking spaces

Guidance on the use of non-breaking spaces ("hard spaces") –  , {{nbsp}},  , {{thinsp}} – is given in some sections below; {{nowrap}} may also be useful in controlling linebreaks in some situations. Not all situations in which hard spaces or {{nowrap}} may be appropriate are described. For further information see Wikipedia:Manual of Style § Non-breaking spaces and Wikipedia:Line-break handling.

Chronological items

Statements likely to become outdated

See also: Wikipedia:Manual of Style/Words to watch § Relative time references, and Wikipedia:As of

Except on pages updated regularly (e.g. the "Current events" portal), terms such as now, currently, to date, so far, soon, and recently should usually be avoided in favor of phrases such as during the 1990s, since 2010, and in August 1969. For current and future events, use phrases like as of November 2024 or since the beginning of 2024 to signal the time-dependence of the information; use the template {{as of}} in conjunction.

Relative-time expressions are acceptable for very long periods, such as geological epochs: Humans diverged from other primates long ago, but only recently developed state legislatures.

Dates, months, and years

• These requirements do not apply to dates in quotations or titles; see Wikipedia:Manual of Style § Quotations.
• Special rules apply to citations; see Wikipedia:Citing sources § Citation style.
• See also Wikipedia:Overview of date formatting guidelines.

Formats

Acceptable date formats

General use	Only where brevity is helpful (refs, tables, infoboxes, etc.)	Comments
2 September 2001	2 Sep 2001
September 2, 2001	Sep 2, 2001	A comma follows the year unless followed by other punctuation that replaces the comma: The weather on March 12, 2005, was clear and warm Everyone remembers July 20, 1969 – when man first landed on the Moon
2 September	2 Sep	Omit year only where there is no risk of ambiguity: The 2012 London Olympics ran from 25 July to 12 September January 1 is New Year's Day
September 2	Sep 2
No equivalent for general use	2001-09-02	Use yyyy-mm-dd format only with Gregorian dates from 1583 onward.
September 2001	Sep 2001

• Dates should be linked only when they are relevant to the subject (as discussed at Wikipedia:Linking § Chronological items).
• For issues related to dates in sortable tables, see Help:Sorting § Configuring the sorting and Help:Sorting § Date sorting problems, or consider using {{dts|Nov 1, 2008}}.
• Phrases such as Fourth of July (or July Fourth, but not July 4th), Cinco de Mayo, Seventh of March Speech and Sete de Setembro are proper names, to which rules for dates do not apply (A typical Fourth of July celebration includes fireworks).

Unacceptable date formats (except in external titles and quotes)

Unacceptable	Acceptable	Comments
Sep. 2	Sep 2	Do not add a dot to the day or to an abbreviated month
9. June	9 June or June 9
9 june june 9		Months are capitalized
9th June June 9th the 9th of June		Do not use ordinals (1st, 2nd, 3rd, etc.)
09-06 06-09		Do not use these formats
09 June June 09		Do not use a leading zero in month or day ...
2007-4-15	2007-04-15	... except in all-numeric (yyyy-mm-dd) format
2007/04/15		Do not use separators other than hyphens
07-04-15		Do not abbreviate year to two digits
15-04-2007 04-15-2007 2007-15-04		Do not use dd-mm-yyyy, mm-dd-yyyy or yyyy-dd-mm formats.
2007 April 15 2007 Apr 15		Do not use these formats.
7/2001 7-2001 07-2001 2001-07 2001 July July of 2001	July 2001	Do not use these formats.
July, 2001		No comma between month and year
3 July, 2001	3 July 2001
July 3 2001	July 3, 2001	Comma required between day and year
the '97 elections the 97 elections	the 1997 elections	Do not abbreviate year
Copyright MMII	Copyright 2002	Roman numerals are not normally used for dates
Two thousand one	2001	Years and days of the month are not normally written in words
the first of May May the first	May 1 or 1 May
June 0622	June 622	Do not zero-pad years
sold in the year 1995	sold in 1995	Use "the year" only where needed for clarity (About 1800 ships arrived in the year 1801)

Consistency

• Dates in article body text should all use the same format: She fell ill on 25 June 2005 and died on 28 June, but not She fell ill on 25 June 2005 and died on June 28.
• Publication dates in an article's citations should all use the same format, which may be:
  • the format used in the article body text,
  • an abbreviated format from the "Acceptable date formats" table, provided the day and month elements are in the same order as in dates in the article body, or
  • the format expected in the citation style being used (however, all-numeric date formats other than yyyy-mm-dd must still be avoided).

For example, publication dates within a single article might be in one, but only one, of these formats (among others):

Jones, J. (20 September 2008)

Jones, J. (September 20, 2008)

• Access and archive dates in an article's citations should all use the same format, which may be:
  • the format used for publication dates in the article;
  • the format expected in the citation style adopted in the article (e.g. 20 Sep 2008); or
  • yyyy-mm-dd

For example, access/archive dates within a single article might be in one, but only one, of these formats (among others):

Jones, J. (September 20, 2008) ... Retrieved February 5, 2009.

Jones, J. (20 Sep 2008) ... Retrieved 5 Feb 2009.

Jones, J. (20 September 2008) ... Retrieved 2009-02-05.

When a citation style does not expect differing date formats, it is permissible to normalize publication dates to the article body text date format, and/or access/archive dates to either, with date consistency being preferred.

Strong national ties to a topic

For any given article, the choice of date format and the choice of national variety of English (see WP:Manual of Style#Strong national ties to a topic) are independent issues.

• Articles on topics with strong ties to a particular English-speaking country should generally use the date format most commonly used in that nation. For the United States this is (for example) July 4, 1976; for most other English-speaking countries it is 4 July 1976.
• Articles related to Canada or Israel may use either format with (as always) consistency within each article. (see Retaining existing format)
• In some topic areas, the customary format differs from the usual national one: for example, articles on the modern US military, including US military biographical articles, use day-before-month, in accordance with US military usage.

Retaining existing format

See also: Wikipedia:Manual of Style § Retaining the existing variety

• If an article has evolved using predominantly one date format, this format should be used throughout the article, unless there are reasons for changing it based on strong national ties to the topic or consensus on the article's talk page.
• The date format chosen in the first major contribution in the early stages of an article (i.e., the first non-stub version) should continue to be used, unless there is reason to change it based on strong national ties to the topic or consensus on the article's talk page.
• Where an article has shown no clear sign of which format is used, the first person to insert a date is equivalent to "the first major contributor".

Era style

"WP:BCE" redirects here. For Wikipedia:Basic copyediting, see WP:BCE (disambiguation).

• The default calendar eras are the Anno Domini and Common Era (respectively, BC and AD and BCE and CE). Either convention may be appropriate for use in Wikipedia articles depending on the article context. Apply Wikipedia:Manual of Style § Retaining existing styles with regard to changes from one era to the other.
  • Use either the BC–AD or the BCE–CE notation consistently within the same article. Exception: do not change direct quotations, titles, etc.
  • An article's established era style should not be changed without reasons specific to its content; seek consensus on the talk page first (applying Wikipedia:Manual of Style § Retaining existing styles) by opening a discussion under a heading using the word era, and briefly stating why the style should be changed.
  • BCE and CE or BC and AD are written in upper case, unspaced, without a full stop (period, .), and separated from the numeric year by a space (5 BC, not 5BC). It is advisable to use a non-breaking space.
  • AD may appear before or after a year (AD 106, 106 AD); the other abbreviations appear only after (106 CE, 3700 BCE, 3700 BC).
  • In general, do not use CE or AD unless required to avoid ambiguity (e.g. The Norman Conquest took place in 1066 not 1066 CE nor AD 1066) or awkwardness (January 1, 1 AD not January 1, 1).
    • On the other hand, Plotinus lived at the end of the 3rd century AD will avoid confusion, and depending on context one- and two-digit years may look more natural with an era marker (born in 2 AD).
    • In He did not become king until 55 CE the era marker makes it clear that 55 does not refer to the new king's age (or write He did not become king until the year 55).
    • Do not write from 450 BCE to 200 but rather from 450 to 200 BCE or from 450 BCE to 200 BCE (and definitely from 100 BCE to 200 CE). (see Ranges)
• Uncalibrated (bce) radiocarbon dates: Calibrated and uncalibrated dates can diverge widely, and some sources distinguish the two only via BCE or BC (for calibrated dates) versus bce, bc or b.c. (uncalibrated). Avoid giving uncalibrated dates except in direct quotations, and even then a footnote or square-bracketed note [like this] should note that the date is uncalibrated or (ideally) give the calibrated date.
• BP or YBP: In scientific and academic contexts, BP (before present) or YBP (years before present) are often used. (Present in this context conventionally refers to January 1, 1950.) Write 3000 years BP or 3000 YBP or 3000 years before present but not forms such as 3000 before present and 3000 years before the present. If one of the abbreviated forms is used, link to Before present on first use: The Jones artifact was dated to 4000 YBP, the Smith artifact to 5000 YBP.
• Other era systems may be appropriate in an article. In such cases, dates should be followed by a conversion to Anno Domini or Common Era and the first instance should be linked: Qasr-al-Khalifa was built in 221 AH (836 CE), or in 836 AD (221 AH).
  • Astronomical year numbering follows the Common Era and does not require conversion, but the first instance of a non-positive year should still be linked: The March equinox passed into Pisces in year −67.

Julian and Gregorian calendars

See also: Old Style and New Style dates

A date can be given in any appropriate calendar, as long as it is (at the minimum) given in the Julian calendar or the Gregorian calendar or both, as described below. For example, an article on the early history of Islam may give dates in both Islamic and Julian calendars. Where a calendar other than the Julian or Gregorian is used, the article must make this clear.

• Current events are dated using the Gregorian calendar.
• Dates of events in countries using the Gregorian calendar at that time are given in the Gregorian calendar. This includes some of the Continent of Europe from 1582, the British Empire from 14 September 1752, and Russia from 14 February 1918 (see Adoption of the Gregorian calendar).
• Dates before 15 October 1582 (when the Gregorian calendar was first adopted in some places) are normally given in the Julian calendar. The Julian day and month should not be converted to the Gregorian calendar, but the start of the Julian year should be assumed to be 1 January (see below for more details).
• Dates for Roman history before 45 BC are given in the Roman calendar, which was neither Julian nor Gregorian. When (rarely) the Julian equivalent is certain, it may be included.
• For dates in early Egyptian and Mesopotamian history, Julian or Gregorian equivalents are often uncertain. Follow the consensus of reliable sources, or indicate their divergence.

The dating method used should follow that used by reliable secondary sources (or if reliable sources disagree, that used most commonly, with an explanatory footnote).

Where it's not obvious that a given date should be given in Julian alone or in Gregorian alone, consider giving both styles, for example by using {{OldStyleDate}}. If a date appears without being specified as Old Style or New Style, tagging that date with {{which calendar?}} will the page to Category:Articles containing ambiguous dates for further attention.

If there is a need to mention Old or New Style dates in an article (as in the Glorious Revolution), a footnote should be provided on the first usage, stating whether the New Style refers to a start of year adjustment or to the Gregorian calendar (it can mean either).

At some places and times, the new year began on a date other than 1 January. For example, in England and its colonies until 1752, the year began on Annunciation Day, 25 March; see the New Year article for other styles. In writing about historical events, however, years should be assumed to have begun on 1 January (see the example of the execution of Charles I in "Differences in the start of the year"); if there is reason to use another start-of-year date, this should be noted.

Ranges

• A simple year–year range is written using an en dash (– or {{ndash}}) not an em dash, hyphen or slash; this dash is unspaced (that is, with no space on either side); and the range's end year is usually given in full:
  • 1881–1886;  1881–1992 (not 1881–86;  1881 – 1992)
  • Markup: 1881{{ndash}}1886 or 1881–1886
  • Two-digit ending years (1881–82, but never 1881–882 or 1881–2) may be used in any of the following cases: (1) two consecutive years; (2) infoboxes and tables where space is limited (using a single format consistently in any given table column); and (3) in certain topic areas if there is a very good reason, such as matching the established convention of reliable sources.
  • The slash notation (2005/2006) may be used to signify a fiscal year or other special period, if that convention is used in reliable sources.
• Other "simple" ranges use an unspaced en dash as well:
  • day–day: 5–7 January 1979;  January 5–7, 1979;  elections were held March 5–8.
  • month–month: the 1940 peak period was May–July;  the peak period was May–July 1940;  (but the peak period was May 1940 – July 1940 uses a spaced en dash; see below)
• If at least one item on either side of the en dash contains a space, then a spaced en dash ({{snd}}) is used. For example:
  • between specific dates in different months: They travelled June 3 – August 18, 1952;  They travelled 3 June – 18 August 1952
  • between dates in different years:
    • Charles Robert Darwin (12 February 1809 – 19 April 1882) was an English naturalist ...
    • Markup: 12{{nbsp}}February 1809{{snd}}19{{nbsp}}April 1882 or 12 February 1809 – 19 April 1882
    • Abraham Lincoln (February 12, 1809 – April 15, 1865) was the 16th President of ...
  • between months in different years: The exception was in force August 1892 – January 1903;  The Ghent Incursion (March 1822 – January 1, 1823) was ended by the New Year's Treaty
    • Markup: March 1822{{snd}}January{{nbsp}}1, 1823 or March 1822 – January 1, 1823
  • Where era designations, circa or other modifiers are present: reigned 5 BC – 12 AD;  reigned c. 1393 – 1414. (see § Uncertain, incomplete, or approximate dates)

• For ranges "to present", constructions such as 1982–present (with unspaced ndash), January 1, 2011 – present (spaced ndash), or January 2011 – present (spaced ndash) may be used, but other constructions may be more appropriate in prose (see § Statements likely to become outdated). In tables and infoboxes where space is limited, pres. may be used (1982–pres.). Do not use incomplete-looking constructions such as 1982– and 1982–... .

• For a person still living: Serena Williams (born September 26, 1981) is a ..., not (September 26, 1981 – ) or (born on September 26, 1981).

  Do not use * to indicate born; use b. only where space is limited e.g. tables and infoboxes; use either born or b. consistently in any given table column.

• Where birthdate is unknown: John Smith (died May 1, 1622) or John Smith (died 1622)

  Do not use † to indicate died; use d. only where space is limited, with consistency within any given table column.

• An overnight period may be expressed using a slash between two contiguous dates: the night raids of 30/31 May 1942 or raids of 31 May / 1 June 1942.

  Or use an en dash: (unspaced) raids of 30–31 May 1942;  (spaced) raids of 31 May – 1 June 1942.

• Use an en dash, or a word such as from or between, but not both: from 1881 to 1886 (not from 1881–1886);  between June 1 and July 3 (not between June 1 – July 3)
• The {{Age}} template can keep ages current in infoboxes and so on:
  • {{age|1989|7|23}} returns: 35
  • {{age|1989|7|23}}-year-old returns: 35-year-old
  • {{age|1989|7|23}} years old returns: 35 years old
• Date mathematics templates are available for other age calculations.

Uncertain, incomplete, or approximate dates

• To indicate "around", "approximately", or "about", the use of the spaced, unitalicised form c. 1291 (or the {{circa}} template) is preferred over circa, ca, ca., around, approximately, or approx.:
  • At the birth of Roger Bacon (c. 1214) ...
  • John Sayer (c. 1750 – 2 October 1818) ...
  • the Igehalkid dynasty of Elam, c. 1400 BC ...
• Where both endpoints of a range are approximate, c. should appear before each date (the two-argument form of {{circa}} does this):
  • Dionysius Exiguus (c. 470 – c. 540 ... (not Dionysius Exiguus (c. 470 – 540) ...)
  • Rameses III (reigned c. 1180 – c. 1150 BCE) ... (not Rameses III (reigned c. 1180 – 1150 BCE) ...)
• Where birth/death limits have been inferred from known dates of activity:
  • Offa of Mercia (before 734 – 26 July 796) ...
  • Robert Menli Lyon (1789 – after 1863) ...
  • Ambrose Gwinnett Bierce (June 24, 1842 – after December 26, 1913) ...
• When birth and death dates are unknown, but the person is known to have been active ("flourishing") during certain years, fl., [[Floruit|fl.]], or {{fl.}} may be used:
  • Jacobus Flori (fl. 1571–1588) ...

The linked forms should not be used on disambiguation pages, and "active" followed by the range is a better alternative for occupations not relating to the composition of works, whether it be musical, grammatical, historical, or any other such work.

• When a date is known to be either of two years (e.g. from a regnal or AH year conversion, or a known age at death):
  • Anne Smith (born 1912 or 1913; died 2013) ...
• Other forms of uncertainty should be expressed in words, either in article text or in a footnote: April 14, 1224 (unattested date). Do not use a question mark (1291?), because it fails to communicate the nature of the uncertainty.
• Ranges in which c., after, fl. or similar forms appear‍—‌whether on one or both sides‍—‌employ a spaced endash ({{snd}}) and ideally a non-breaking space should follow very short modifiers such as c. and fl.. Examples: 1896 – after 1954, c. 470 – c. 540, c. 470 – c. 540. Markup: 1896{{snd}}after 1954, {{c.}}{{nbsp}}470{{snd}}{{c.}}{{nbsp}}540, {{c.|470|540}}

Times of day

Context determines whether the 12- or 24-hour clock is used. In all cases, colons separate hours, minutes, and (where present) seconds, e.g. 1:38:09 pm or 13:38:09. Use figures (11 a.m. or 12:45 p.m.) rather than words (twelve forty-five p.m.).

• 12-hour clock times end with lower-case a.m. or p.m., or am or pm, preceded by a non-breaking space, e.g. 2:30 p.m. or 2:30 pm (markup: 2:30{{nbsp}}p.m. or 2:30{{nbsp}}pm), not 2:30p.m. or 2:30pm. Hours should not have a leading zero (e.g. 2:30 p.m., not 02:30 p.m.). Usually, use noon and midnight rather than 12 pm and 12 am; whether "midnight" refers to the start or the end of a date should be explicitly specified unless clear from the context. Where several times that are all a.m. or all p.m. appear in close proximity, then a.m. or p.m. need be given only once if there is no risk of confusion.
• 24-hour clock times have no a.m., p.m., noon or midnight suffix, and include a colon (15:30 not 1530). Hours under 10 should have a leading zero (08:15). The time 00:00 refers to midnight at the start of a date, 12:00 to noon, and 24:00 to midnight at the end of a date, but 24 should not be used for the first hour of the next day (e.g. use 00:10 for ten minutes after midnight, not 24:10).

Time zones

Give dates and times appropriate to the time zone where an event took place. For example, the date of the attack on Pearl Harbor should be December 7, 1941 (Hawaii time/​date). Give priority to the place at which the event had its most significant effects; for example, if a hacker in Monaco attacked a Pentagon computer in the US, use the time zone for the Pentagon, where the attack had its effect. In some cases, the best solution may be to add the date and time in Coordinated Universal Time (UTC). For example:

     8 p.m. Eastern Standard Time on January 15, 2001 (01:00 UTC, January 16)

Alternatively, include just the UTC offset:

     21:00 British Summer Time (UTC+1) on 27 July 2012

Rarely, the time zone in which an event took place has since changed; for example, China to 1949 was divided into five time zones, whereas all of modern China is UTC+8. Similarly, the term "UTC" is not appropriate for dates before this system was adopted in 1960; Universal Time (UT) is the appropriate term for the mean time at the prime meridian (Greenwich) when it is unnecessary to specify the precise definition of the time scale. Be sure to show the UTC or offset appropriate to the clock time in use at the time of the event, not the modern time zone, if they differ.

Days of the week

• Days of the week are capitalized (Sunday, Wednesday).
• Where space is limited (tables, infoboxes, etc.) an en dash may be used for a range (Monday–Thursday).

Seasons of the year

• Seasons are uncapitalized (a hot summer) except when personified: Old Man Winter's bleak greys relent as Spring begins to show her colors.
• Avoid the use of seasons to refer to a particular time of year (winter 1995) as such uses are ambiguous: the seasons are six months apart in the northern and southern hemispheres, and areas near the equator have only wet and dry seasons.
  • Unambiguous alternatives include early 1995;  the first quarter of 1995;  January to March 1995;  spent the southern summer in Antarctica.
• Referring to a season by name is appropriate when it is part of a formal or conventional name or designation (annual mid-winter festival;  the autumn harvest;  2018 Winter Olympics;  Times Fall Books Supplement;  Details appeared in Quarterly Review, Summer 2015;  The Court's winter term).

Decades

• To refer to a decade as a chronological period per se (not with reference to a social era or cultural phenomenon), always use four digits as in the 1980s. Do not use the 1980's, the 1980‑ies, or the 1980s' (unless a possessive is actually meant).
  • Prefixes should be hyphenated (the mid‑1980s;  pre‑1960s social attitudes).
• For a social era or cultural phenomenon associated with a particular decade:
  • Two digits (with a preceding apostrophe) may be used as an alternative to four digits, but only if this is a well-established phrase seen in reliable sources (the Roaring '20s,  the Gay '90s,  condemning the '60s counterculture, but grew up in 1960s Boston, moving to Dallas in 1971, and do not write the 90's;  the 90s;  or the 90s').
  • A third alternative (where seen in reliable sources) is to spell the decade out, capitalized: changing attitudes of the Sixties.

Centuries and millennia

The sequence of numbered years in dates runs ... 2 BC, 1 BC, 1 AD, 2 AD ...; there is no "year zero".

• Treat the 1st century AD as years 1–100, the 17th century as 1601–1700, and the second millennium as 1001–2000; similarly, the 1st century BC/BCE was 100–1 BC/BCE, the 17th century BC/BCE was 1700–1601 BC/BCE, and the second millennium 2000–1001 BC/BCE.
• Centuries and millennia are identified using either "Arabic" numerals (the 18th century) or words (the second millennium). When used adjectivally they contain a hyphen (nineteenth-century painting or 19th-century painting). Do not use superscripts (19^th century).
• Do not capitalize (the best Nineteenth-century paintings;  during the Nineteenth Century)
• Do not use Roman numerals (XVIII century).
• The 18th century refers to the period (1701–1800), while strictly the 1700s refers either to (1700–1799) or (1700–1709)
  • When using forms such as the 1900s, ensure that there is no ambiguity as to whether the century or just its first decade is meant.
• See WP:Manual of Style § En dashes for use of hyphens and dashes in obscure situations.

Long periods of time

• When the term is frequent, combine yr (years) or ya (years ago) with k (thousand): kya, kyr; M (million): Mya, Myr; and b (short-scale billion): bya, byr. (See Year § Abbreviations yr and ya for more information.)
• In academic contexts, SI annus-based units are often used: ka (kiloannus), Ma (megaannus), and Ga (gigaannus). (See Year § SI prefix multipliers for more information.)
• Show the meaning parenthetically, and consider linking to the appropriate section of the Year article (see links above) on first occurrence and where the use is a standalone topic of interest. In source quotations, use square brackets: "a measured Libby radiocarbon date of 35.1 mya [million years ago] required calibration ..."

Numbers

Numbers as figures or words

Information on specific situations is scattered elsewhere on this page.

Generally, in article text:

• Integers from zero to nine are spelled out in words.
• Integers greater than nine expressible in one or two words may be expressed either in numerals or in words (16 or sixteen, 84 or eighty-four, 200 or two hundred). When written as words, numbers from 21 to 99 are hyphenated (including when part of a larger number): fifty-six or fifty-six thousand but five hundred or five thousand.
• Other numbers are given in numerals (3.75, 544) or in forms such as 21 million. Markup: 21{{nbsp}}million
  • Billion and trillion are understood to represent their short-scale values of 10⁹ (1,000,000,000) and 10¹² (1,000,000,000,000), respectively. Keep this in mind when translating articles from non-English or older sources.
  • M (unspaced, capitalized) or bn (unspaced), respectively, may be used for "million" or "billion" after a number, when the word has been spelled out at the first occurrence (She received £70 million and her son £10M).
  • SI prefixes and symbols, such as mega- (M), giga- (G) and tera- (T), should be used only with units of measure as appropriate to the field, and not to express large quantities in other contexts. Examples of misuse: In a population of 1.3G people, 300 megadeaths would be expected.
  • Sometimes, the variety of English used in an article may suggest the use of a numbering system other than the Western thousands-based system. For example, the South Asian numbering system is conventionally used for certain things (especially monetary amounts) in South Asian English. This is discouraged in Wikipedia articles by WP:Manual of Style § Opportunities for commonality.
    • When it is done anyway, for contextually important reasons, link the first spelled-out instance of each quantity (e.g. [[crore]], which yields: crore). If no instances are spelled out, provide a note after the first instance, directing the reader to the article about the numbering system.
    • Provide a conversion to Western numbers for the first instance of each quantity (the templates {{lakh}}, {{crore}}, and {{lakh crore}} may be used for this purpose), and provide conversions for subsequent instances if they do not overwhelm the content of the article. For example, write three crore (thirty million). When converting a currency amount, use the exchange rate that applied at the time being written about; the {{INRConvert}} template can be used for this purpose.
    • Group digits in Western thousands-based style (e.g., 30,000,000; not 3,00,00,000); see § Delimiting (grouping of digits), below.
    • The variety of English does not uniquely determine the method of numbering in an article. Other considerations – such as conventions used in mathematics, science, and engineering – may also apply. The choice and order of formats and conversions is a matter of editorial discretion and consensus at the article.

Notes and exceptions:

• Avoid beginning a sentence with a figure:
  • Use: There were many matches; 23 ended in a draw. Or: There were many matches. Twenty-three ended in a draw.
  • Not: There were many matches. 23 ended in a draw.
  • Use: No elections were held in 1945 and 1950.
  • Not: 1945 and 1950 had no elections. (Nor: Nineteen forty-five and 1950 had no elections – comparable numbers should be both written in words or both in figures.)
  • Opening a sentence with a proper name or technical term that begins with a numeral can usually be avoided by rewording:
    • Prefer: Typically, 1-naphthylamine is synthesized via the Feldenshlager–Glockenspiel process. Or: Feldenshlager–Glockenspiel is the process typically used in the synthesis of 1-naphthylamine.
    • Avoid: 1-Naphthylamine is typically synthesized via the Feldenshlager–Glockenspiel process.
• In tables and infoboxes, quantities are expressed in figures (Years in office: 5); but numbers within a table's explanatory text and comments follow the general rule.
• Numbers in mathematical formulae are never spelled out (3 < π < 22/7, not three < π < 22 sevenths).
• Sport scores and vote tallies should be given as figures, even if in the zero-to-nine range (a 25–7 victory; and passed with 7 ayes, 2 nays, and 1 abstention).
• Comparable values should be all spelled out or all in figures, even if one of the numbers would normally be written differently: patients' ages were five, seven, and thirty-two or ages were 5, 7 and 32, but not ages were five, seven and 32.
• Adjacent quantities not comparable should usually be in different formats: twelve 90-minute volumes or 12 ninety-minute volumes, not 12 90-minute volumes or twelve ninety-minute volumes.
  • Avoid awkward juxtapositions: On February 25, 2011, twenty-one more were chosen, not On February 25, 2011, 21 more were chosen.
• Sometimes figures and words carry different meanings; for example, Every locker except one was searched implies there is a single exception (without specifying which), while Every locker except 1 was searched means that only locker number 1 was not searched.
• Proper names, technical terms, and the like are never altered: 10 Downing Street,  Nine Inch Nails,  Channel 8,  Seven Samurai,  The Sixth Sense,  Chanel No. 5,  Fourth Estate,  The Third Man,  Second Coming,  First Amendment,  Zero Hour!,  Less Than Zero
• Figures as figures: Use a figure when the figure itself (its glyph, shape, etc.) is meant: a figure-8 pattern; in the shape of the numeral 6. (See WP:Manual of Style/Text formatting § Words as words.)
• Only figures are used with unit symbols (2 min not two min), but figures or words may be used with unit names (2 minutes or two minutes), within the guidelines above. (See also table: General guidelines on unit names and symbols.)

Ordinals

• For guidance on choosing between e.g. 15th and fifteenth, see § Numbers as figures or words.
• In "suffix" forms, use two-letter suffixes: 1st, 2nd, 3rd, 4th and so on (2nd Battalion not 2d Battalion). Do not superscript (123^rd).
• Do not use ordinals for dates (see MOS:BADDATE)
• In English text, do not use a dot (.) or the ordinal mark (º) The ordinal mark is acceptable in names, quotations, etc. from languages that conventionally use it. An Italian example: 313° Gruppo Addestramento Acrobatico not 313° Acrobatic Training Group or the 313°.
• Regnal numbers are normally written with Roman numerals (without suffix, e.g. Elizabeth II not Elizabeth IInd or Elizabeth 2nd).

Number ranges

As with date ranges (see above), number ranges in general, such as page ranges, should state the full value of both the beginning and end of the range, with an en dash between, e.g. pp. 1902–1911 or entries 342–349. Forms such as 1901–11 and 342–9 may be used where space is limited (such as in tables and infoboxes), or where a citation style formally requires it. (As usual, quotations are not changed.)

Singular versus plural

• Nouns following simple fractions are singular (took 1⁄4 dose;  net change was −1⁄2 point;  3⁄2 dose).
• Nouns following mixed numbers are plural (11⁄2 doses;  another 43⁄4 miles).
• Nouns following the lone, unsigned digit 1 are singular, but those following other decimal numbers (i.e. base-10 numbers not involving fractions) are plural (increased 0.7 percentage points;  365.25 days;  paid 5 dollars per work hour, 1 dollar per travel hour, 0 dollars per standby hour;  increased by 1 point but net change +1 points;  net change −1 points;  net change 1.0 points).
• The same rules apply to numbers given in words (one dose;  one and one-half doses;  zero dollars;  net change of negative one points).

Fractions and ratios

• Spelled-out fractions are hyphenated: seven-eighths.
• Where numerator and denominator can each be expressed in one word, a fraction is usually spelled out (e.g. a two-thirds majority;  moved one-quarter mile); use figures if a fraction appears with a symbol (e.g. 1⁄4 mi – markup: {{frac|1|4}} mi, not a quarter of a mi or one-quarter mi). A common exception is a series of values: The distances were 1+1⁄4, 2⁄3 and 1⁄2 mile, respectively.
• Mixed numbers are usually given in figures, unspaced (not Fellini's film 8 1⁄2 or 8-1⁄2 but Fellini's film 8+1⁄2 – markup: {{frac|8|1|2}}). In any case the integer and fractional parts should be consistent (not nine and 1⁄2).
• Metric (SI) measurements generally use decimals, not fractions (5.25 mm, not 51⁄4 mm).
• Non-metric (imperial and US customary) measurements may use fractions or decimals (51⁄4 inches; 5.25 inches); the practice of reliable sources should be followed, and within-article consistency is desirable.
• In science and mathematics articles, mixed numbers are rarely used (use ⁠4/3⁠ the original rather than 1⁠1/3⁠ times the original voltage). The use of {{frac}} is discouraged in favor of one of these styles:
  • $\textstyle {\frac {1}{2}}$ – markup: <math>\textstyle\frac{1}{2}</math>
  • ⁠1/2⁠ – markup: {{sfrac|1|2}}
  • 1/2 – markup: 1/2
• Do not use precomposed fraction characters such as ½ (deprecated markup: ½ or ½). Exception: In special situations such as articles on chess matches, a precomposed ½ may be used if that is the only fraction appearing in the article.
• Ordinal suffixes such as -th should not be used with fractions expressed in figures (not each US state has 1/50th of the Senate's votes; 1/8th mile, but one-fiftieth of the Senate's votes; 1/8 mile; one-eighth mile).
• Dimensionless ratios (i.e. those without accompanying units) are given by placing a colon between integers, or placing to between numbers-as-words: favored by a 3:1 ratio or a three-to-one ratio, not a 3/1 ratio or a 3–1 ratio.
  • Use a colon (spaced) when one or more decimal points is present (a 3.5 : 1 ratio – markup: a 3.5 : 1 ratio).
  • Do not use the colon form where units are involved (dissolve using a 3 ml : 1 g ratio)‍—‌instead see ratios section of table at § Unit names and symbols, below.

Decimals

• A period/full point (.) – never a comma – is used as the decimal point (6.57, not 6,57).
• Numbers between −1 and +1 require a leading zero (0.02, not .02); exceptions are sporting performance averages (.430 batting average) and commonly used terms such as .22 caliber.
• Indicate repeating digits with an overbar e.g. 14.31{{overline|28}} gives 14.3128. (Consider explaining this notation on first use.) Do not write e.g. 14.31(28) because it resembles notation for uncertainty.

Grouping of digits

• Digits should be grouped and separated either by commas or by narrow gaps (never a period/full point).

  Grouping with commas

  Left of the decimal point, five or more digits are grouped into threes separated by commas (e.g. 12,200; 255,200 km; 8,274,527th; 1⁄86,400).

  Numbers with exactly four digits left of the decimal point may optionally be grouped (either 1,250 or 1250), provided that this is consistent within each article.

  When commas are used left of the decimal point, digits right of the decimal point are not grouped (i.e. should be given as an unbroken string).

  Markup: {{formatnum:}} produces this formatting.

  Grouping with narrow gaps

  Digits are grouped both sides of the decimal point (e.g. 6543210.123456; 520.01234 °C; ⁠101325/760⁠).

  Digits are generally grouped into threes. Right of the decimal point, usual practice is to have a final group of four in preference to leaving an "orphaned" digit at the end (99.1234567, but 99.1234567 would also be acceptable). In mathematics-oriented articles long strings may be grouped into fives (e.g. 3.14159265358979323846...).

  This style is especially recommended for articles related to science, technology, engineering or mathematics.

  Markup: Templates {{val}} or {{gaps}} may be used to produce this formatting. Note that use of any space character as a separator in numbers, including non-breaking space, is problematic for screen readers. (See § Non-breaking spaces.) Screen readers read out each group of digits as separate numbers (e.g. 30 000 is read as "thirty zero zero zero".)

• Delimiting style should be consistent throughout a given article.
  • Either use commas or narrow gaps, but not both in the same article.
  • Either group the thousands in a four-digit number or do not, but not mixed use in the same article.
  • However, grouping by threes and fives may coexist.
• An exception is made for four-digit page numbers or four-digit calendar years. These should never be grouped (not sailed in 1,492, but dynasty collapsed around 10,400 BC or by 13727 AD, Vega will be the northern pole star).

Percentages

• In the body of non-scientific/non-technical articles, percent (American English) or per cent (British English) are commonly used: 10 percent; ten percent; 4.5 per cent. Ranges are written ten to twelve per cent or ten to twelve percent, not ten–twelve per cent or ten to twelve %.
• In the body of scientific/​technical articles, and in tables and infoboxes of any article, the symbol % (unspaced) is more common: 3%, not 3 % or three %. Ranges: 10–12%, not 10%–12% or 10 to 12%.
• When expressing the difference between two percentages, do not confuse a percentage change with a change in percentage points.

Scientific and engineering notation

• Scientific notation always has a single nonzero digit to the left of the point: not 60.22×10²², but 6.022×10²³.
• Engineering notation is similar, but adjusted so that the exponent is a multiple of three: 602.2×10²¹.
• Avoid mixing scientific and engineering notations (A 2.23×10² m² region covered by 234.0×10⁶ grains of sand).
• In a table column (or other presentation) in which all values can be expressed with a single power of 10, consider giving e.g. ×10⁷ once in the column header, and omitting it in the individual entries. (Markup: {{e|7}})
• In both notations, the number of digits indicates the precision. For example, 5×10³ means rounded to the nearest thousand; 5.0×10³ to the nearest hundred; 5.00×10³ to the nearest ten; and 5.000×10³ to the nearest unit.

Markup: {{val}} and {{e}} may be used to format exponential notation.

Uncertainty and rounding

• Where explicit uncertainty information (such as a margin of error) is available and appropriate for inclusion, it may be written in various ways:
  • (1.534 ± 0.035) × 10²³ m
  • 12.34 m² ± 5% (not used with scientific notation)
  • 15.34 ^+0.43
    _−0.23 × 10²³ m
  • 1.604(48) × 10⁻⁴ J (equivalent to (1.604 ± 0.048) × 10⁻⁴ J)
  • Polls estimated Jones's share of the vote would be 55 percent, give or take about 3 percent
  • Markup: {{+-}}, {{su}}, and {{val}} may be used to format uncertainties.
• Where explicit uncertainty is unavailable (or is unimportant for the article's purposes) round to an appropriate number of significant digits; the precision presented should usually be conservative. Precise values (often given in sources for formal or matter-of-record reasons) should be used only where stable and appropriate to the context, or significant in themselves for some special reason.
  • The speed of light is defined to be 299,792,458 m/s
  • but Particle velocities eventually reached almost two-thirds the 300-million-metre-per-second speed of light.
  • checks worth $250 (equivalent to $1,800 in 2016) (not $1,845.38 in 2016)
  • The city's 1920 population was 10,000 (not population was 9,996 – an official figure unlikely to be accurate at full precision)
  • but The town was ineligible because its official census figure (9,996) fell short of the statutory minimum of ten thousand (unusual case in which the full-precision official figure is truly informative)
  • The accident killed 337 passengers and crew, and 21 people on the ground (likely that accurate and precise figures were determined)
  • At least 800 persons died in the ensuing mudslides (unlikely that any precise number can be accurate, even if an official figure is issued)
  • or Officials listed 835 deaths, but the Red Cross said dozens more may have gone unreported (in reporting conflicting information, give detail sufficient to make the contrast intelligible)
  • The jury's award was $8.5 million (not $8,462,247.63). The appeals court reduced this to $3,000,001 (one dollar in actual damages, the remainder in punitive damages).
• The number of decimal places should be consistent within a list or context (The response rates were 41.0 and 47.4 percent, respectively, not 41 and 47.4 percent), unless different precisions are actually intended.
• It may sometimes be appropriate to note the lack of uncertainty information, especially where such information is normally provided and necessary for full interpretation of the figures supplied.
  • A local newspaper poll predicted 52 percent of the vote would go to Smith, but did not include information on the uncertainty of this estimate
• The {{undue precision}} template may be added to figures appearing to be overprecise.
• Avoid using "approximately", "about", and similar terms with figures that have merely been approximated or rounded in a normal and expected way, unless the reader might otherwise be misled.
  • The tallest player was 6 feet 3 inches (not ... about 6 feet 3 inches – heights are conventionally reported only to the nearest inch, even though greater precision may be available in principle)
  • but The witness said the assailant was about 5 feet 8 inches tall ("about" because here the precise value is unknown, with substantial uncertainty)
• The reader may be assumed to interpret large round numbers (100,000 troops) as approximations. Writing a quantity in words (one hundred thousand troops) can further emphasize its approximate nature.
• See § Unit conversions below for precision issues when converting units.

Non-base-10 notations

• In computer-related articles, use the prefix 0x for hexadecimal, 0 for octal, and 0b for binary, unless there is a strong reason to use some other notation. Explain these prefixes in the article's introduction or on first use.
• In all other articles, use <sub> to create subscripts: 137₉, 201₃. Markup: 137<sub>9</sub>, 201<sub>3</sub>
• For bases above 10, use symbols conventional for that base (as seen in reliable sources) e.g. for base 16 use 0–9 and A–F.

Mathematical formulae

Main page: Wikipedia:Manual of Style/Mathematics

For the display of a mathematical formula, there are multiple options, covered in detail at WP:Manual of Style/Mathematics § Typesetting of mathematical formulae. One uses special MediaWiki <math>...</math> markup using LaTeX syntax, which is capable of complex formulae; the other relies on conventionalized HTML formatting of simple formulae.

On the user end, the <math> markup is displayed as a PNG image by default. Logged-in users can optionally have it rendered in MathML, or in HTML (via MathJax); detailed instructions are at Help:Displaying a formula.

Do not put <math> markup in headings; it is an accessibility problem.

Units of measurement

Unit choice and order

Quantities are typically expressed using an appropriate "primary unit", displayed first, followed, when appropriate, by a conversion in parentheses e.g. 200 kilometres (120 mi). For details on when and how to provide a conversion, see the section § Unit conversions. The choice of primary units depends on the circumstances, and should respect the principle of "strong national ties", where applicable:

• In non-scientific articles with strong ties to the United States, the primary units are US customary (pounds, miles, feet, inches, etc.)
• In non-scientific articles with strong ties to the United Kingdom, the primary units for most quantities are metric or other internationally used units, except that:
  • UK engineering-related articles, including those on bridges and tunnels, generally use the system of units that the topic was drawn up in (but road distances are given in imperial units, with a metric conversion – see next bullet);
  • the primary units for distance/​length, speed and fuel consumption are miles, miles per hour, and miles per imperial gallon (except for short distances or lengths, where miles are too large for practical use);
  • the primary units for personal height and weight are feet​/inches and stones/​pounds;
  • imperial pints are used for quantities of draught beer/​cider and bottled milk;
• In all other articles, the primary units chosen will be SI units, non-SI units officially accepted for use with the SI, or such other units as are conventional in reliable-source discussions of the article topic (such as revolutions per minute (rpm) for rotational speed, hands for heights of horses, et cetera).

Special considerations:

• Quantities set via definition (as opposed to measured quantities) should be given first in the units used in the definition, even if this makes the structure of presentation inconsistent: During metrification, the speed limit was changed from 30 mph (48 km/h) to 50 km/h (31 mph).
  • Or use about to emphasize which is the statutory, exact value: ...from 30 mph (about 48 km/h) to 50 km/h (about 31 mph).
• Nominal quantities (e.g. 2 × 4 lumber) require consideration of whether the article is concerned with the item's actual dimensions or merely with its function. In some cases, the nominal quantity may suffice; in others it may be necessary to give the nominal size (often in non-SI units), the actual size in non-SI units, and the actual size in SI units.
• Whenever a conversion is used, ensure that the precision of the converted quantity in the article is comparable to the precision of the value given by the source (see § Unit conversions).
• Where the article's primary units differ from the units given in the source, the {{convert}} template's |order=flip flag can be used; this causes the original unit to be shown as secondary in the article, and the converted unit to be shown as primary: {{convert|200|mi|km|order=flip}} → The two cities are 320 kilometres (200 mi) apart.

Unit conversions

Where English-speaking countries use different units for the same quantity, provide a conversion in parentheses: the Mississippi River is 2,320 miles (3,734 km) long; the Murray River is 2,508 kilometres (1,558 mi) long. But in science-related articles, supplying such conversion is not required unless there is some special reason to do so.

• Where an imperial unit is not part of the US customary system, or vice versa – and in particular, where those systems give a single term different definitions – a double conversion may be appropriate: Rosie weighed 80 kilograms (180 lb; 12 st 8 lb) (markup: {{convert|80|kg|lb stlb}}); The car had a fuel economy of 5 L/100 km (47 mpg_‑US; 56 mpg_‑imp) (markup: {{convert|5|L/100km|mpgus mpgimp|abbr=on}}).
• Generally, conversions to and from metric units and US or imperial units should be provided, except:
  • When inserting a conversion would make a common or linked expression awkward (The four-minute mile).
  • When units are part of the subject of a topic – nautical miles in articles about the history of nautical law (5 nautical miles), SI units in scientific articles (a 600-kilometer asteroid), yards in articles about American football – it can be excessive to provide conversions every time a unit occurs. It might be best to note that this topic will use the units (possibly giving the conversion factor to another familiar unit in a parenthetical note or a footnote), and link the first occurrence of each unit but not give a conversion every time it occurs.
• Converted quantity values should use a level of precision similar to that of the source quantity value, so the Moon is 380,000 kilometres (240,000 mi) from Earth, not (236,121 mi). Small numbers, especially if approximate, may need to be converted to a range where rounding would cause a significant distortion, so about one mile (1–2 km), not about one mile (2 km). Be careful especially when your source has already converted from the units you're now converting back to. This may be evidenced by multiples of common conversion factors in the data, such as 160 km (from 100 miles). See false precision.
• {{convert}} (and other conversion templates) can be used to convert and format many common units.
• In a direct quotation, always retain the source units. Any conversions can be supplied either in the quote itself (in square brackets, following the original measurement) or in a footnote. See footnoting and citing sources.
• {{Units attention}} may be added to articles needing general attention regarding choice of units and unit conversions.

Unit names and symbols

Definitions:

• Examples of unit names: foot, metre, kilometre, (US: meter, kilometer).
• Examples of unit symbols: ft, m, km.

• Unit names and symbols should follow the practice of reliable sources.
• In prose, unit names should be given in full if used only a few times, but symbols may be used when a unit (especially one with a long name) is used repeatedly, after spelling out the first use (e.g. Up to 15 kilograms of filler is used for a batch of 250 kg).
  • Exception: Certain units are generally represented by their symbols (e.g. °C rather than degrees Celsius) even on first use, though their unit names may be used for emphasis or clarity (conversion of degrees Celsius to degrees Fahrenheit).
  • Exception: Consider using inches (but not in.) in place of in where the latter might be misread as a preposition‍—‌but not where the value is followed by a parenthesized conversion e.g. bolts 5 in (12.7 cm) long, or is part of such a conversion (bolts 12.7 cm (5 in) long).
• Where space is limited, such as in tables, infoboxes, parenthetical notes, and mathematical formulas, unit symbols are preferred.
• Units unfamiliar to general readers should be presented as a name–symbol pair on first use, linking the unit name (Energies rose from 2.3 megaelectronvolts (MeV) to 6 MeV).
• Ranges use unspaced en dash ({{ndash}}) if only one unit symbol is used at the end (e.g. 5.9–6.3 kg), and spaced en dash ({{snd}}) if two symbols are used (e.g. 3 μm – 1 mm); ranges in prose may be specified using either unit symbol or unit names, and units may be stated either after both numerical values or after the last (all acceptable: from 5.9 to 6.3 kilograms; from 5.9 kilograms to 6.3 kilograms; from 5.9 to 6.3 kg; from 5.9 kg to 6.3 kg).
• Length–width, length–width–height and similar dimensions may be separated by the multiplication sign (× or ×) or the word by.
  • With the multiplication sign, each number should be followed by a unit name or symbol (if appropriate):
    • 1 m × 3 m × 6 m, not 1 × 3 × 6 m, (1 × 3 × 6) m, nor 1 × 3 × 6 m³
    • a metal plate 1 ft × 3 ft × 0.25 in
    • a railroad easement 10 ft × 2.5 mi
  • The × symbol is preceded by a space (preferably non-breaking), and followed by a space (which may also be non-breaking in short constructions).
  • With by, the unit need be given only once if it is the same for all values: 1 by 3 by 6 metres or 1 by 3 by 6 m
  • The unspaced letter x may be used in common terms such as 4x4.

General guidelines on use of units

Aspect	Guideline	Acceptable	Unacceptable
Unit names and symbols	Except as listed in the § Specific units table below, unit symbols are uncapi­tal­ized unless they are derived from a proper name, in which case the first letter (of the base unit symbol, not of any prefix) is capitalized.	8 kg 100 kPa	8 Kg 100 kpa
	Unit symbols are undotted.	38 cm of rope	38 cm. of rope
	Unit names are given in lower case except: where any word would be capital­ized, or where otherwise specified in the SI brochure or this Manual of Style.	He walked several miles. Miles of trenches were dug.	A Gallon equals 4 Quarts.
	The spelling of certain unit names (some of which are listed in § Specific units, below) varies with the variety of English followed by the article.
	Write unit names and symbols in upright (roman) type, except where emphasizing in context.	10 m 29 kilograms	10 m 29 kilograms
		Thus each two-liter jug contained only two quarts.
	Do not use precomposed unit symbol characters.		㎓, ㎦, ㎍, ㎖, ㎉
Numeric values	Do not spell out numbers before unit symbols ...	12 min	twelve min
	... but words or figures may be used with unit names.	twelve minutes 12 minutes
	Use a non-breaking space ({{nbsp}} or  ) between a number and a unit symbol, or use {{nowrap}} ...	29 kg (markup: 29 kg or {{nowrap|29 kg}})	29kg
	... though with certain symbols no space is used (see "Specific units" table below) ...	23° 47′ 22″	23 ° 47 ′ 22 ″
	... and a normal space is used between a number and a unit name.	29 kilograms (markup: 29 kilograms)
	To form a value and a unit name into a compound adjective use a hyphen or hyphens ...	a five-day holiday a five-cubic-foot box a 10-centimeter blade
	... but a non-breaking space (never hyphen) separates a value and unit symbol.	a blade 10 cm long	a 10-cm blade
Plurals	SI unit names are pluralized by adding the appropriate -s or -es suffix ...	1 ohm; 10 ohms
	... except for these irregular forms.	1 henry; 10 henries 1 hertz; 10 hertz 1 lux; 10 lux 1 siemens; 10 siemens	10 henrys 10 hertzes 10 luxes
	Some non-SI units have irregular plurals.	1 foot; 10 feet	10 foots
		1 stratum; 10 strata (unusual)	10 stratums
	Unit symbols (in any system) are identical in singular and plural.	grew from 1 in to 2 in grew from 1 inch to 2 inches grew from one to two inches	grew from 1 in to 2 ins
Powers	Format exponents using <sup>, not special characters.	km2 (markup: km<sup>2</sup>)	km² (km&#178;)
	Or use squared or cubed (after the unit being modified).	ten metres per second squared	ten metres per squared second
	For areas or volumes only, square or cubic may be used (before the unit being modified).		ten metres per square second
		tons per square mile
	sq or cu may be used with US customary or imperial units, but not with SI units.	15 sq mi 3 cu ft	15 sq km 3 cu m
Products	Indicate a product of unit names with either a hyphen or a space.	foot-pound foot pound	footpound foot⋅pound
	Indicate a product of unit symbols with &sdot; or &nbsp;.	ms = millisecond m⋅s or m s = metre-second
	Exception: In some topic areas, such as power engineer­ing, certain products take neither space nor &sdot;. Follow the practice of reliable sources in the article's topic area.	Wh, VA, Ah kWh, MVA, GAh
	To pluralize a product of unit names, pluralize only the final unit. (Unit symbols are never pluralized.)	ten foot-pounds	ten feet-pounds
Ratios, rates, densities	Indicate a ratio of unit names with per.	meter per second	meter/second
	Indicate a ratio of unit symbols with a forward slash (/), followed by either a single symbol or a parenthesized product of symbols – do not use multiple slashes. Or use −1, −2, etc.	metre per second m/s m⋅s−1	mps
		kg/(m⋅s) kg⋅m−1⋅s−1	kg/m⋅s kg/m/s
	To pluralize a ratio of unit names, pluralize only the numerator unit. (Unit symbols are never pluralized.)	ten newton-metres per second 10 N⋅m/s
	Some of the special forms used in the imperial and US customary systems are shown here ...	mph = miles per hour mpg = miles per gallon psi = pounds per square inch
	... but only the slash or negative exponent notations are used with SI (and other metric) units.	g/m2 g⋅m−2	gsm
		km/h km⋅h−1	kph
Prefixes	Prefixes should not be separated by a space or hyphen.	25 kilopascals	25 kilo pascals 25 kilo-pascals
	Prefixes are added without contraction, except as shown here:	kilohm megohm hectare	kiloohm megaohm hectoare
	The centi-, deci-, deca-, and hecto- prefixes should generally be avoided; exceptions include centimetre, decibel, hectolitre, hectare, and hectopascal.	100 metres 0.1 km	1 hectometre
	Do not use M for 103, MM for 106, or B for 109 (except as noted elsewhere on this page for M and B, e.g. for monetary values)	3 km 8 MW 125 GeV	3 Mm 8 MMW 125 BeV
Mixed units	Mixed units are traditionally used with the imperial and US customary systems ...	a wall 1 ft 1 in thick a wall 1 foot 1 inch thick a man 6 feet 2 inches tall a 6-foot 2-inch man a 6 ft 2 in man	1 ft , 1 in (no comma) 1 foot , 1 inch a man 6 foot 2 tall a 6-foot 2 man
		1 US fl pt 8 oz 1 US fl pt 8 US fl oz
	... and in expressing time durations ...	1:30:07 1:30  1 h 30 min 7 s 01h 30m 07s	1:30′07″ 1 hr 30 min 7 sec 1 h 30 m 7 s
	... but are not normally used in SI.	1.33 m 133 cm	1 m 33 cm

Note to table:

Specific units

• The following table lists only units that need special attention.
• The SI Brochure should be consulted for guidance on use of other SI and non-SI units.

Guidelines on specific units

Group	Name	Symbol	Comment
Length, speed	inch foot	in ft	Do not use ′ (′), ″ (″), apostrophe (') or quote (").
	foot per second	ft/s (not fps)
	hand	h or hh	Equal to 4 inches; used in measurement of horses. A dot may be followed by additional inches e.g. 16.2 hh indicates 16 hands 2 inches.
	knot	kn (not kt or kN)
	metre meter (US)	m
	micron	μm (not μ)	Markup: μm  Link to micrometre (for which micron is a synonym) on first use.
	astronomical unit	au (not A.U., ua)	The preferred option is au. Articles that already use AU may switch to au or continue with AU; seek consensus on the talk page.
	mile miles per hour nautical mile	mi mph nmi or NM (not nm or M)	In nautical and aeronautical contexts where there is risk of confusion with nautical miles, consider writing out references to statute miles as e.g. 5 statute miles rather than simply 5 miles.
Volume, flow	cubic centimetre cubic centimeter (US)	cm3	Markup: cm<sup>3</sup>
		cc	Non-SI abbreviation used for certain engine displacements; link to Cubic centimetre on first use.
	imperial fluid ounce imperial pint imperial quart imperial gallon US fluid ounce US fluid pint US fluid quart US gallon	imp fl oz imp pt imp qt imp gal US fl oz US fl pt US fl qt US gal	US or imperial (or imp) must be specified; fluid or fl must be specified for fluid ounces and US units, except with gallon. (Without fluid, ounce is ambiguous – versus avoirdupois ounce or troy ounce – and US pint or US quart are ambiguous – versus US dry pint or US dry quart.)
	cubic foot	cu ft (not cf)	Write five million cubic feet, 5,000,000 cu ft, or 5×106 cu ft, not 5 MCF.
	cubic foot per second	cu ft/s (not cfs)
	litre liter (US)	l or L	The symbol l (lowercase "el") in isolation (i.e. outside forms as ml) is easily mistaken for the digit 1 or the capital letter I ("eye").
Mass, weight, force, density, pressure	gram kilogram	g kg	Not gramme, kilogramme
	long ton short ton	long ton short ton	Spell out in full.
	pound per square inch	psi
	tonne metric ton (US)	t (not mt or MT)
	troy ounce	oz t	t or troy must be specified. Articles about precious metals, black powder, and gemstones should always specify whether ounces and pounds are avoirdupois or troy.
	troy pound	lb t
	carat	carat	Used to express masses of gemstones and pearls.
Purity	carat or karat	k or Kt	A measure of purity for gold alloys. (Do not confuse with the unit of mass with the same spelling.)
Time	second minute hour	s min h	Do not use &prime; (′), &Prime; (″), apostrophe (') or quote (") for minutes or seconds. See also the hours–minutes–seconds formats for time durations described in the Unit names and symbols table.
	year	a	Use a only with an SI prefix multiplier (a rock formation 540 Ma old, not Life expectancy rose to 60 a).
		y or yr	See § Long periods of time for all affected units.
Information, data	bit	bit (not b or B)	See also § Quantities of bytes and bits, below. Do not confuse bit/second or byte/second with baud (Bd).
	byte	B or byte (not b or o)
	bit per second	bit/s (not bps, b/s)
	byte per second	B/s or byte/s (not Bps, bps, b/s)
Angle
	arcminute	′	Markup: &prime;  (prime ′ not apostrophe/​single quote '). No space (47′, not 47 ′).
	arcsecond	″	Markup: &Prime;  (double prime ″ not double-quote "). No space (22″, not 22 ″).
	degree	°	Markup: &deg; (degree ° not masculine ordinal º or ring  ̊ ). No space (23°, not 23 °).
Temperature	degree Fahrenheit	°F (not F)	Markup: &deg;. Use a non-breaking space: 12{{nbsp}}&deg;C, not 12&deg;C nor 12&deg;{{nbsp}}C (12 °C, not 12°C nor 12° C).
	degree Celsius (not degree centigrade)	°C (not C)
	kelvin (not degree kelvin)	K (not °K)
Energy	calorie small calorie gram calorie	cal	In certain subject areas, calorie is convention­ally used alone. Articles following this practice should specify on first use whether the use refers to the small calorie or to the kilocalorie (large calorie). Providing conversions to SI units (usually calories to joules or kilocalories to kilojoules) may also be useful. A kilocalorie (kcal) is 1000 calories. A calorie (small calorie) is the amount of energy required to heat 1 gram of water by 1 °C. A kilocalorie is therefore also a kilogram calorie.
	kilocalorie large calorie kilogram calorie (not Calorie – can be ambiguous)	kcal

Quantities of bytes and bits

In quantities of bits and bytes, the prefixes kilo- (symbol k or K), mega- (M), giga- (G), tera- (T), etc., are ambiguous in general usage. The meaning may be based on a decimal system (like the standard SI prefixes), meaning 10³, 10⁶, 10⁹, 10¹², etc., or it may be based on a binary system, meaning 2¹⁰, 2²⁰, 2³⁰, 2⁴⁰, etc. The binary meanings are more commonly used in relation to solid-state memory (such as RAM), while the decimal meanings are more common for data transmission rates, disk storage and in theoretical calculations in modern academic textbooks.

Follow these recommendations when using these prefixes in Wikipedia articles:

• Following the SI standard, a lower-case k should be used for "kilo-" whenever it means 1000 in computing contexts, whereas a capital K should be used instead to indicate the binary prefix for 1024 according to JEDEC. If, under the exceptions detailed further below, the article otherwise uses IEC prefixes for binary units, use Ki instead.
• Do not assume that the binary or decimal meaning of prefixes will be obvious to everyone. Explicitly specify the meaning of k and K as well as the primary meaning of M, G, T, etc. in an article ({{BDprefix}} is a convenient helper). Consistency within each article is desirable, but the need for consistency may be balanced with other considerations.
• The definition most relevant to the article should be chosen as primary for that article, e.g. specify a binary definition in an article on RAM, decimal definition in an article on hard drives, bit rates, and a binary definition for Windows file sizes, despite files usually being stored on hard drives.
• Where consistency is not possible, specify wherever there is a deviation from the primary definition.
• Disambiguation should be shown in bytes or bits, with clear indication of whether in binary or decimal base. There is no preference in the way to indicate the number of bytes and bits, but the notation style should be consistent within an article. Acceptable examples include:
  • A 64 MB (64 × 1024²-byte) video card and a 100 GB (100 × 1000³-byte) hard drive
  • A 64 MB (64 × 2²⁰-byte) video card and a 100 GB (100 × 10⁹-byte) hard drive
  • A 64 MB (67,108,864-byte) video card and a 100 GB (100,000,000,000-byte) hard drive
• Avoid inconsistent combinations such as A 64 MB (67,108,864-byte) video card and a 100 GB (100 × 1000³-byte) hard drive. Footnotes, such as those seen in Power Macintosh 5500, may be used for disambiguation.
• Unless explicitly stated otherwise, one byte is eight bits (see Byte § History).

The IEC prefixes kibi- (symbol Ki), mebi- (Mi), gibi- (Gi), etc., are generally not to be used except:

• when the majority of cited sources on the article topic use IEC prefixes;
• in a direct quote using the IEC prefixes;
• when explicitly discussing the IEC prefixes; or
• in articles in which both types of prefix are used with neither clearly primary, or in which converting all quantities to one or the other type would be misleading or lose necessary precision, or declaring the actual meaning of a unit on each use would be impractical.

Currencies and monetary values

"WP:CURRENCY" redirects here. For the WikiProject focusing on articles about currencies, see Wikipedia:WikiProject Numismatics.

See also: Wikipedia:WikiProject Numismatics/Style § Article titles

Choice of currency

• In country-specific articles, such as Economy of Australia, use the currency of the subject country.
• In non-country-specific articles such as Wealth, use US dollars (US$123 on first use, generally $123 thereafter), euros (€123), or pounds sterling (£123).

Currency names

• Do not capitalize the names or denominations of currencies, currency subdivisions, coins and banknotes: not a Five-Dollar bill, four Quarters, and one Penny total six Dollars one Cent but a five-dollar bill, four quarters, and one penny total six dollars one cent. Exception: where otherwise required, as at the start of a sentence or in such forms as Australian dollar.
• To pluralize euro use the standard English plurals (ten euros and fifty cents), not the invariant plurals used for European Union legislation and banknotes (ten euro and fifty cent). For the adjectival form, use a hyphenated singular (a two-euro pen and a ten-cent coin).
• Link the first occurrence of lesser-known currencies (Mongolian tögrögs).

Currency symbols

• In general, the first mention of a particular currency should use its full, unambiguous signifier (e.g. A$52), with subsequent references using just the appropriate symbol (e.g. $88), unless this would be unclear. Exceptions:
  • In an article referring to multiple currencies represented by the same symbol (e.g. the dollars of the US, Canada, Australia, New Zealand, and other countries – see Currency symbols § dollar variants) use the full signifier (e.g. US$ or A$, but not e.g. $US123 or $123 (US)) each time, except (possibly) where a particular context makes this both unnecessary and undesirable.
  • In articles entirely on EU-, UK- and/or US-related topics, all occurrences may be shortened (€26, £22 or $34), unless this would be unclear.
• For the British pound sterling (GBP), use the £ symbol, with one horizontal bar, not the double-barred ₤ (which is used for Italian lira). For non-British currencies that use pounds or a pound symbol (e.g. the Egyptian pound, E£) use the symbol conventionally preferred for that currency.
• If there is no common English abbreviation or symbol, follow the ISO 4217 standard. See also List of circulating currencies.

Formatting

• A period (full stop, .) – never a comma – is used as the decimal point ($6.57, not $6,57).
• For the grouping of digits (e.g. £1,234,567) see § Grouping of digits, above.
• Do not place a currency symbol after the accompanying numeric figures (e.g. 123$, 123£, 123€) unless that is the normal convention for that symbol when writing in English: smaller British coins include 1p, 2p, and 5p denominations.
• Currency abbreviations that come before the numeric value are unspaced if they consist of a nonalphabetic symbol alone (£123 or €123), or end with a nonalphabetic symbol (R$123); but spaced if completely alphabetic (R 123 or JD 123).
• Ranges should be expressed giving the currency signifier just once: $250–300, not $250–$300.
• million and billion should be spelled out on first use, and (optionally) abbreviated M or bn (both unspaced) thereafter: She received £70 million and her son £10M; the school's share was $250–300 million, and the charity's $400–450M.
• In general, a currency symbol should be accompanied by a numeric amount e.g. not He converted his US$ to A$ but He converted his US dollars to Australian dollars or He exchanged the US$100 note for Australian dollars.
  • Exceptions may occur in tables and infoboxes where space is limited e.g. Currencies accepted: US$, SFr, GB£, €. It may be appropriate to wikilink such uses, or add an explanatory note.

Conversions

• Conversions of less-familiar currencies may be provided in terms of more familiar currencies – such as the US dollar, euro or pound sterling – using an appropriate rate (which is often not the current exchange rate). Conversions should be in parentheses after the original currency, along with the convert-to year; e.g. grant in 2001 was 10,000,000 Swedish kronor ($1.4M, €970,000, or £850,000 as of 2009)
• For obsolete currencies, provide an equivalent (formatted as a conversion) if possible, in the modern replacement currency (e.g. decimal pounds for historical pre-decimal pounds-and-shillings), or a US-dollar equivalent where there is no modern equivalent.
• In some cases, it may be appropriate to provide a conversion accounting for inflation or deflation over time. See {{Inflation}} and {{Inflation-fn}}.
• When converting among currencies or inflating/deflating, it is rarely appropriate to give the converted amount to more than three significant figures; typically, only two significant figures are justified: grant in 2001 was 10,000,000 Swedish kronor ($1.4M, €970,000, or £850,000), not ($1,390,570, €971,673 or £848,646)

Common mathematical symbols

See also: Wikipedia:Manual of Style/Mathematics and Help:Displaying a formula

• The Insert menu below the editing window gives a more complete list of math symbols, and allows symbols to be inserted without the HTML encoding (e.g. ÷) shown here.
• Spaces are placed to left and right when a symbol is used with two operands (the sum 4 + 5), but no space is used when there is one operand (the value +5). Exception: spaces are usually omitted in inline fractions formed with /: 3/4 not 3 / 4.
• The {{mvar}} (for single-letter variables) and {{math}} (for more complicated expressions) templates are available to display mathematical formulas in a manner distinct from surrounding text.
• The {{nbsp}} and {{nowrap}} templates may be used to prevent awkward linebreaks.

Common mathematical symbols

Symbol name	Example	Markup	Comments
Plus / positive	x + y	{{math|''x'' + ''y''}}
	+y	{{math|+''y''}}
Minus / negative	x − y	{{math|''x'' − ''y''}}	Do not use hyphens (-) or dashes ({{ndash}} or {{mdash}}).
	−y	{{math|−''y''}}
Plus-minus / minus-plus	41.5 ± 0.3	41.5 ± 0.3
	−(±a) = ∓a	{{math|1=−(±''a'') = ∓''a''}}
Multiplication, dot	x ⋅ y	{{math|''x'' ⋅ ''y''}}
Multiplication, cross	x × y	{{math|''x'' × ''y''}}	Do not use the letter x to indicate multiplication. However, an unspaced x may be used as a substitute for "by" in common terms such as 4x4.
Division, obelus	x ÷ y	{{math|''x'' ÷ ''y''}}
Equal / equals	x = y	{{math|1=''x'' = ''y''}} or {{math|''x'' {{=}} ''y''}}	Note the use of 1= or {{=}} to make the template parameters work correctly
Not equal	x ≠ y	{{math|''x'' ≠ ''y''}}
Approx. equal	π ≈ 3.14	{{math|''π'' ≈ 3.14}}
Less than	x < y	{{math|''x'' &lt; ''y''}}
Less or equal	x ≤ y	{{math|''x'' &le; ''y''}}
Greater than	x > y	{{math|''x'' &gt; ''y''}}
Greater or equal	x ≥ y	{{math|''x'' &ge; ''y''}}

Geographical coordinates

For draft guidance on, and examples of, coordinates for linear features, see Wikipedia:WikiProject Geographical coordinates/Linear.

Quick guide:

Quick how-to

To add 57°18′22″N 4°27′32″W to the top of an article, use {{Coord}}, thus:

{{Coord|57|18|22|N|4|27|32|W|display=title}}

These coordinates are in degrees, minutes, and seconds of arc.

"title" means that the coordinates will be displayed next to the article's title at the top of the page (in desktop view only; title coordinates do not display in mobile view) and before any other text or images. It also records the coordinates as the primary location of the page's subject in Wikipedia's geosearch API.

To add 44.1124°N 87.9130°W / 44.1124; -87.9130 to the top of an article, use either

{{Coord|44.1124|N|87.9130|W|display=title}}

(which does not require minutes or seconds but does require the user to specify north/ south and east/west) or

{{Coord|44.1124|-87.9130|display=title}}

(in which the north and east are presumed by positive values while the south and west are negative ones). These coordinates are in decimal degrees.

• Degrees, minutes and seconds, when used, must each be separated by a pipe ("|").
• Map datum must be WGS84 if possible (except for off-Earth bodies).
• Avoid excessive precision (0.0001° is <11 m, 1″ is <31 m).
• Maintain consistency of decimal places or minutes/seconds between latitude and longitude.
• Latitude (N/S) must appear before longitude (E/W).

Optional coordinate parameters follow the longitude and are separated by an underscore ("_"):

• dim: dim:N (viewing diameter in metres)
• region: region:R (ISO 3166-1 alpha-2 or ISO 3166-2 code)
• type: type:T (landmark or city(30,000), for example)

Other optional parameters are separated by a pipe ("|"):

• display

  |display=inline (the default) to display in the body of the article only,

  |display=title to display at the top of the article only (in desktop view only; title coordinates do not display in mobile view), or

  |display=inline,title to display in both places.

• name

  name=X to label the place on maps (default is PAGENAME)

Thus: {{Coord|44.1172|-87.9135|dim:30_region:US-WI_type:event

|display=inline,title|name=accident site}}

Use |display=title (or |display=inline,title) once per article, for the subject of the article, where appropriate.

• Per WP:ORDER, the template is placed at the bottom of the article in the 'end matter', after any navigation templates, but before all categories, including the {{DEFAULTSORT}} template. The {{coord}} template may also be placed within an infobox, instead of at the bottom of the article.
• For full details, refer to {{Coord/doc}}.
• Additional guidance is available at obtaining coordinates and converting coordinates.

Geographical coordinates on Earth should be entered using a template to standardise the format and to provide a link to maps of the coordinates. As long as the templates are adhered to, a robot performs the functions automatically.

First, obtain the coordinates. Avoid excessive precision.

The {{Coord}} template offers users a choice of display format through user styles, emits a Geo microformat, and is recognised (in the title position) by the "nearby" feature of Wikipedia's mobile apps and by external service providers such as Google Maps and Google Earth, and Yahoo. Infoboxes automatically emit {{Coord}}.

The following formats are available.

• For degrees only (including decimal values): {{coord|dd|N/S|dd|E/W}}
• For degrees/minutes: {{coord|dd|mm|N/S|dd|mm|E/W}}
• For degrees/minutes/seconds: {{coord|dd|mm|ss|N/S|dd|mm|ss|E/W}}

where:

• dd, mm, ss are the degrees, minutes and seconds, respectively;
• N/S is either N for northern or S for southern latitudes;
• E/W is either E for eastern or W for western longitudes;
• negative values may be used in lieu of S and W to denote Southern and Western Hemispheres

For example:

For the city of Oslo, located at 59° 55′ N, 10° 44′ E:

{{coord|59|55|N|10|44|E}} – which becomes 59°55′N 10°44′E

For a country, like Botswana, less precision is appropriate:

{{coord|22|S|24|E}} – which becomes 22°S 24°E

Higher levels of precision are obtained by using seconds:

{{coord|33|56|24|N|118|24|00|W}} – which becomes 33°56′24″N 118°24′00″W

Coordinates can be entered as decimal values

{{coord|33.94|S|118.40|W}} – which becomes 33.94°S 118.40°W / -33.94; -118.40

Increasing or decreasing the number of decimal places controls the precision. Trailing zeros should be used as needed to ensure that both values have the same level of precision.

London Heathrow Airport, Amsterdam, Jan Mayen and Mount Baker are examples of articles that contain geographical coordinates.

Generally, the larger the object being mapped, the less precise the coordinates should be. For example, if just giving the location of a city, precision greater than 100 meters is not needed unless specifying a particular point in the city, for example the central administrative building. Specific buildings or other objects of similar size would justify precisions down to 10 meters or even one meter in some cases (1″ ~15 m to 30 m, 0.0001° ~5.6 m to 10 m).

The final field, following the E/W, is available for attributes such as type:, region:, or scale: (the codes are documented at Template:Coord/doc#Coordinate parameters).

When adding coordinates, please remove the {{coord missing}} tag from the article, if present.

For more information, see the geographical coordinates WikiProject.

Templates other than {{coord}} should use the following variable names for coordinates: lat_d, lat_m, lat_s, lat_NS, long_d, long_m, long_s, long_EW.

See also

• Wikipedia:Naming conventions (numbers and dates)
• Wikipedia:Date formattings
• m:Help:Date formatting feature at Meta
• m:Help:Calculation § Displaying numbers and numeric expressions at Meta