Wikipedia:Manual of Style/Dates and numbers

This part of the Manual of Style aims to achieve consistency in the use and formatting of numbers, dates, times, measurements, currencies and coordinates in English Wikipedia articles. Consistent standards make articles easier to read, write, and edit. Where this manual provides options, consistency should be maintained within an article, unless there is a good reason to do otherwise. In direct quotations, the original text should be preserved.

Edit warring over optional styles (such as 14 February and February 14) is unacceptable. If an article has been stable in a given style, it should not be converted without a style-independent reason. Where in doubt, defer to the style used by the first major contributor.

In June 2005, the Arbitration Committee decided that, when either of two styles is acceptable, it is inappropriate for an editor to change an article from one to the other without substantial reason; for example, with respect to the British date format as opposed to the American format, it would be acceptable to change from American format to British if the article concerned a British subject. In February 2006, the Committee ruled, "Wikipedia does not mandate styles in many different areas; these include (but are not limited to) American vs. British spelling, date formats, and citation style. Where Wikipedia does not mandate a specific style, editors should not attempt to convert Wikipedia to their own preferred style, nor should they edit articles for the sole purpose of converting them to their preferred style, or removing examples of, or references to, styles which they dislike." They also ruled that, "Users who focus in a disruptive way on an issue or subject may be banned from editing with respect to that issue or subject."

Non-breaking spaces

See also: Wikipedia:Manual of Style § Non-breaking spaces, and Wikipedia:Line break handling

• Use a non-breaking space (also known as a hard space) to prevent the end-of-line displacement of elements that would be awkward at the beginning of a new line:
  • in expressions in which figures and abbreviations (or symbols) are separated by a space (e.g. 17 kg, AD 565, 2:50 pm);
  • between the date number and month name (e.g. 26 May or May 26); and
  • in other places where breaking across lines might be disruptive to the reader, especially in infoboxes, such as £11 billion, May 2024, 5° 24′ 21.12″ N, Boeing 747, after the number in a numbered address (e.g. 123 Fake Street) and before Roman numerals at the end of phrases (e.g. World War II and Pope Benedict XVI).
• A hard space can be produced with the HTML code   instead of the space bar: 19 kg yields a non-breaking 19 kg.
• A literal hard space, such as one of the Unicode non-breaking space characters, should not be used, since some web browsers will not load them properly when editing.
• Hard spaces can also be produced by using the {{nowrap}} template: {{nowrap|8 sq ft}} produces a non-breaking 8 sq ft. This is especially useful for short constructions requiring two or more hard spaces, as in the preceding example. Template {{nowrap}} has the disadvantage that if the enclosed text starts or ends with a space, these spaces are forced outside in the resulting HTML, and unpredicted breaks may occur. If   occurs right before {{nowrap}}, or at the start of text within {{nowrap}}, some browsers allow a break at that point.
• Unlike normal spaces, multiple hard spaces are not compressed by browsers into a single space.

Chronological items

Precise language

See also: Wikipedia:As of and Wikipedia:Manual of Style (words to watch) § Relative time references

Avoid statements that date quickly, except on pages that are regularly updated, like current events pages. Avoid words such as now and soon (unless their intended meaning is clear), currently and recently (except on rare occasions where they are not redundant), or phrases such as in modern times and the sixties. Instead, when writing about past events use more precise phrases such as during the 1990s or in August 1969. For future and current events, use phrases such as as of May 2024 or since the beginning of 2010 that indicate the time-dependence of the information to the reader.

To help editors keep information up to date, statements about current and future events may be used with the as of technique. This is done by using the {{as of}} template to tag information that may become dated quickly: {{as of|2024}} produces the text As of 2024 and categorizes the article appropriately. This technique is not an alternative to using precise language. For instance, one should not replace since the start of 2005 with {{as of|2005}} because some information (the start of 2005) would be lost; instead, use either the plain text or a more advanced feature of {{as of}} such as {{as of|2005|alt=since the start of 2005}}.

Time of day

Context determines whether the 12- or 24-hour clock is used; in both, colons separate hours, minutes and seconds (e.g. 1:38:09 pm or 13:38:09).

• 12-hour clock times end with dotted or undotted lower-case a.m. or p.m., or am or pm, preceded by a space (e.g. 2:30 p.m. or 2:30 pm, not 2:30p.m. or 2:30pm). Hours denoted by a single digit should not have a leading zero (e.g. 2:30 p.m., not 02:30 p.m.). A hard space (see above) is advisable (2:30 pm or {{nowrap|2:30 p.m.}}). Use noon and midnight rather than 12 pm and 12 am; whether midnight refers to the start or the end of a date will need to be specified unless it is clear from the context.
• 24-hour clock times have no a.m., p.m., noon or midnight suffix. Hours under 10 should have a leading zero (e.g. 08:15). 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 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 of day is normally expressed in figures rather than being spelled out. For details, and information on time intervals (e.g. 5 minutes), see Numbers as figures or words, below.

Day, month and season names

See Wikipedia:Manual of Style (capital letters)#Calendar items

Dates

• Wikipedia does not use ordinal suffixes, articles, or leading zeros. Wikipedia does not insert a comma between month and year; however, a comma is required between day and year.

Incorrect	Correct
9th June the 9th of June	9 June
June 9th	June 9
June, 2001	June 2001
9 June, 2001 09 June 2001	9 June 2001
June 9 2001 June 09, 2001	June 9, 2001

• If a date range is abbreviated, use the formats 5–7 January 1979 or January 5–7, 2002, with an unspaced en-dash.
• A night may be expressed in terms of the two contiguous dates using a slash (the bombing raids of the night of 30/31 May 1942).
• Do not use year-final numerical date formats (DD-MM-YYYY or MM-DD-YYYY), as they are ambiguous: 03/04/2005 could refer to 3 April or to March 4. For consistency, do not use such formats even if the day number is greater than 12.
• Yearless dates (5 March, March 5) are inappropriate unless the year is obvious from the context. There is no such ambiguity with recurring dates, such as January 1 is New Year's Day.
• Year-initial numerical (YYYY-MM-DD) dates (e.g. 1976-05-31) are uncommon in English prose, and should not be used within sentences. However, they may be useful in long lists and tables for conciseness. (For sorting in tables consider using {{sort|2008-11-01|1 November 2008}} or {{sort|2008-11-01|November 1, 2008}}.) Because year-initial dates might be assumed to follow the ISO 8601 standard, which mandates the Gregorian calendar, this format should only be used for dates expressed in the Gregorian calendar and for the years 1583 through 9999.

Full date formatting

In general, the following formats are acceptable:

• Month before day: February 14 and February 14, 1990 (comma required)
• Day before month: 14 February and 14 February 1990 (no comma)

Date formatting in an article is governed by the following three guidelines.

Format consistency

• Dates in article body text should all have the same format.
• Dates in article references should all have the same format.

These requirements apply to dates in general prose and reference citations, but not to dates in quotations or titles.

Strong national ties to a topic

• Articles on topics with strong ties to a particular English-speaking country should generally use the more common date format for that nation. For the US this is month before day; for most others it is day before month. Articles related to Canada may use either format consistently.
• Sometimes the customary format differs from the usual national one: for example, articles on the modern US military use day before month, in accordance with military usage.

Retaining the existing format

• If an article has evolved using predominantly one format, the whole article should conform to it, unless there are reasons for changing it based on strong national ties to the topic.
• The date format chosen by the first major contributor in the early stages of an article should continue to be used, unless there is reason to change it based on strong national ties to the topic. 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".

Dates of birth and death

At the start of an article on an individual, his or her dates of birth and death are provided. For example: "Charles Darwin (12 February 1809 – 19 April 1882) was a British ..." En dashes are preceded by a non-breaking space, except between year-pairs when no spaces are used.

• For an individual still living: "Serena Williams (born September 26, 1981) ...", not "... (September 26, 1981 –) ..."
• When only the years are known, or days and months would be irrelevant detail: "Socrates (470–399 BC) was..."
• When the year of birth is completely unknown, it should be extrapolated from earliest known period of activity: "Offa of Mercia (before 734 – 26 July 796) ..."
• When the year of birth is known only approximately: "Genghis Khan (c. 1162 – August 18, 1227) ..."
• When the years of both birth and death are known only approximately: "Dionysius Exiguus (c. 470 – c. 540) ..."
• When the date of death is completely unknown, it should be extrapolated from last known period of activity: "Robert Menli Lyon (1789 – after 1863) ..."
• When the reign of a sovereign is uncertain: "Rameses III (reigned c. 1180 BCE – c. 1150 BCE) ..."
• When the individual is known to have been alive (flourishing) at certain dates, [[floruit|fl.]] or {{fl.}} is used in articles, not disambiguation pages, to link to floruit, in case the meaning is not familiar: "Osmund (fl. 760–772) ..."
• When the individual is known to have been alive as early as about 660, and to have died in 685: "Aethelwalh (fl. c. 660–685) ..."

In biographical infobox templates, provide age calculation and microformat compatibility with date mathematics templates. See the documentation for those templates in order to use them properly, and Wikipedia:Manual of Style (biographies) for more guidelines on articles about people.

Other date ranges

Dates that are given as ranges should follow the same patterns as given above for birth and death dates.

Linking and autoformatting of dates

Dates should not be linked purely for the purpose of autoformatting (even though linking was previously recommended). Dates should only be linked when they are germane and topical to the subject, as discussed at Wikipedia:Linking#Chronological items.

Longer periods

• Months are expressed as whole words (February, not 2), except in the YYYY-MM-DD format. Unlike some other languages, the names of months and days of the week are capitalized in English. Abbreviations such as Feb. in the United States or Feb in most other countries are used only where space is extremely limited, such as in tables and infoboxes. Do not insert of between a month and a year (April 2000, not April of 2000).

• Seasons. As the seasons are reversed in the northern and southern hemispheres—and areas near the equator tend to have just wet and dry seasons—neutral wording (in early 1990, in the second quarter of 2003, around September) is usually preferable to a "seasonal" reference (summer 1918, spring 1995). Even when the season reference is unambiguous (for instance when a particular location is clearly involved) a date or month may be preferable to a season name, unless there is a logical connection (the autumn harvest). Season names are preferable, however, when they refer to a phase of the natural yearly cycle migration to higher latitudes typically starts in mid-spring). Seasons are normally spelled with a lower-case initial.

• Years
  • Years are normally expressed in digits. Avoid inserting the words the year before the digits (1995, not the year 1995), unless the meaning would otherwise be unclear.
  • Year ranges, like all ranges, are separated by an en dash, not a hyphen or slash: 2005–06 is a two-year range, whereas 2005/06 is a period of twelve months or less such as a sports season or a financial year. A closing CE or AD year is normally written with two digits (1881–86) unless it is in a different century from that of the opening year, in which case the full closing year is given (1881–1986). A closing BCE or BC year is given in full (2590–2550 BCE). While one era signifier at the end of a date range requires an unspaced en dash (12–5 BC), a spaced en dash is required when a signifier is used after the opening and closing years (5 BC – AD 29).
  • To indicate around, approximately, or about, the unitalicised abbreviation c. is preferred over circa, approximately, or approx., and should be spaced (c. 1291). Do not use a question mark for this function (1291?), as this may imply to the reader an uncertainty on the part of Wikipedia editors rather than on the part of reliable historians. c. is preferred over ca.

• Decades
  • Decades as such contain neither an apostrophe nor the suffix -ies (the 1980s, not the 1980's, not the 1980-ies). The two-digit form is never used in reference to the decade as a time span per se.
  • The two-digit form, to which a preceding apostrophe should be added, is used only in reference to a social era or cultural phenomenon that roughly corresponds to and is said to define a decade, and only if it is used in a sourceable stock phrase (the Roaring '20s, the Gay '90s), or when there is a notable connection between the period and what is being discussed in the sentence (a sense of social justice informed by '60s counterculture, but grew up in 1960s Boston, moving to Dallas in 1971). Such an abbreviation should not be used if it would be redundant ('80s Reaganomics) or if it does not have a clear cultural significance and usage (the '10s).

• Centuries and millennia
  • For purposes of written style, the English Wikipedia does not recognize a year 0. Therefore, for dates AD (or CE) the 1st century was 1–100, the 17th century was 1601–1700, and the second millennium was 1001–2000; for dates BC (or BCE) the 1st century was 100–1; the 17th century was 1700–1601, and the second millennium was 2000–1001.
  • Forms such as the 1700s are normally best avoided since it may be unclear whether a 10 or 100 year period is meant (i.e. 1700–1709 or 1700–1799). It should also be noted that the 18th century (1701–1800) and the 1700s (1700–1799) do not span the same period.

Year numbering systems

• Years are numbered according to the traditional western Dionysian era (Common Era).
  • AD and BC are the traditional ways of referring to these eras. CE and BCE are becoming more common in academic and some religious writing. No preference is given to either style.
    • Do not use CE or AD unless the date or century would be ambiguous without it (e.g. "The Norman Conquest took place in 1066" not 1066 CE or AD 1066). On the other hand, Plotinus was a philosopher living at the end of the 3rd century AD.
    • BCE and CE or BC and AD are written in upper case, unspaced, without periods (full stops), and separated from the year number by a space or non-breaking space (5 BC, not 5BC).
    • Use either the BC-AD or the BCE-CE notation, but not both in the same article. AD may appear before or after a year (AD 106, 106 AD); the other abbreviations appear after (106 CE, 3700 BCE, 3700 BC).
    • Do not change from one style to another unless there is substantial reason for the change, and consensus for the change with other editors.
• Uncalibrated (bce) radiocarbon dates: Some source materials will indicate whether a date is calibrated or not simply by a change in capitalization; this is often a source of confusion for the unwary reader. Do not give uncalibrated radiocarbon dates (represented by the lower-case bce unit, occasionally bc or b.c. in some sources), except in directly quoted material, and even then include a footnote, a square-bracketed editor's note [like this], or other indication to the reader what the calibrated date is, or at least that the date is uncalibrated. Calibrated and uncalibrated dates can diverge surprisingly widely, and the average reader does not recognize the distinction between bce and BCE / BC.
• Abbreviations indicating long periods of time ago—such as BP (before present), as well as various annum-based units such as ka (kiloannum), Ma (megaannum) and Ga (gigaannum) are given as full words on first occurrence. Where source quotations use the abbreviations tya or kya (thousand years ago), mya (million years ago), or bya (billion years ago) this should be explained to the reader, as in a measured Libby radiocarbon date of 35.1 mya [million years ago] had to be calibrated ... The tya/kya, mya and bya symbols are deprecated in some fields such as geophysics and geology, but remain common in others, such as anthropology.
  • BP: Do not convert other notations to BP unless you are certain of what you are doing. In some contexts the unit BP is actually defined as "years before January 1, 1950", not "years before the literal present", and the conversion may introduce an error if the date being converted is not a wide approximation (18,000 BP) but a more narrow one or an actual known year. BP years are given as 18,000 BP or spelled out as 18,000 years before present (not 18,000 YBP, 18,000 before present, 18,000 years before the present, or similar.)

Calendars

See also: Old Style and New Style dates

Dates can be given in any appropriate calendar, as long as the date in either the Julian or Gregorian calendars is provided, 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, this must be clear to readers.

• Current events are given in the Gregorian calendar.
• Dates before the adoption of the Gregorian calendar on 15 October 1582 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.
• The Julian or Gregorian equivalent of dates in early Egyptian and Mesopotamian history is often debatable. Follow the consensus of reliable sources, or indicate their divergence.
• Dates of events in countries using the Gregorian calendar 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 the Gregorian calendar article).

The dating method used should follow that used by reliable secondary sources. If the reliable secondary sources disagree, choose the most common used by reliable secondary sources and note the usage in a footnote.

At some places and times, dates other than 1 January were used as the start of the year. The most common English-language convention was the Annunciation Style used in Britain and its colonies, in which the year started on 25 March, Annunciation Day; see the New Year article for a list of other styles. 1 January is assumed to be the opening date for years; if there is reason to use another start-date, this should be stated.

If there is a need to mention Old Style 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).

Time zones

When writing a date, first consider where the event happened and use the time zone there. For example, the date of the Attack on Pearl Harbor should be December 7, 1941 (Hawaii time/date). If it is difficult to judge where, consider what is significant. For example, if a vandal based in Japan attacked a Pentagon computer in the US, use the time zone for the Pentagon, where the attack had its effect. If known, include the UTC date and time of the event in the article, indicating that it is UTC.

Numbers

Numbers as figures or words

As a general rule, in the body of an article, single-digit whole numbers from zero to nine are spelled out in words; numbers greater than nine are commonly rendered in numerals, or in words if they are expressed in one or two words (16 or sixteen, 84 or eighty-four, 200 or two hundred, but 3.75, 544, 21 million). This applies to ordinal numbers as well as cardinal numbers. However there are frequent exceptions to these rules.

• In tables and infoboxes, quantitative data is expressed as numerals; numerals will also fit better in limited space. Numbers within a table's explanatory text and comments should be consistent with the general rule.
• Comparable quantities should be all spelled out or all figures: we may write either 5 cats and 32 dogs or five cats and thirty-two dogs, not five cats and 32 dogs.
• Adjacent quantities which are not comparable should usually be in different formats: twelve 90-minute volumes or 12 ninety-minute volumes is more readable than 12 90-minute volumes or twelve ninety-minute volumes.
• Numbers that begin a sentence are spelled out, since using figures risks the period being read as a decimal point or abbreviation mark; it is often better to recast the sentence than to simply change format, which may produce other problems; e.g. do not use Nineteen forty five and 1950 were important elections for the Labour Party, but rather The elections of 1945 and 1950 were important for the Labour Party.
• The numerical elements of dates and times are not normally spelled out (that is, do not use the seventh of January or twelve forty-five p.m. or Two thousand eight was the year that ... ). However, they should be spelled out where customary in historical references such as Seventh of March Speech and Fifth of November; these are treated as proper names.
• Centuries are given in figures or words using adjectival hyphenation where appropriate: the 5th century BCE; nineteenth-century painting. Neither the ordinal nor the word "century" should be capitalised.
• Simple fractions are normally spelled out; use the fraction form if they occur in a percentage or with an abbreviated unit (1⁄4 yd or a quarter of a yard, but not a quarter of a yd) or if they are mixed with whole numerals.
• Decimal representations containing a decimal point are not spelled out (1.00, 3.14159).
• Numbers in mathematical formulae are never spelled out (3 < π < 22/7, not three < π < 22 sevenths).
• Do not use spelled-out numbers before symbols for units of measurement: write five minutes, 5 minutes, or 5 min, but not five min.
• Measurements, stock prices, and other quasi-continuous quantities are normally stated in figures, even when the value is a small positive integer: 9 mm, The option price fell to 5 within three hours after the announcement.
• When expressing large approximate quantities, it is preferable to write them spelled out, or partly in figures and part as a spelled‑out named number; e.g. one hundred thousand troops may be preferable to 100,000 troops when the size of the force is not known exactly; write Japan has the world's tenth largest population, with about 128 million people (as it is just an approximation to a number likely to be anywhere between 127,500,000 and 128,500,000), but The movie grossed $28,106,731 on its opening day (the exact quantity).
• Sometimes, the variety of English used in an article may call for the use of a numbering system other than the Western thousands-based system. For example, the South Asian numbering system is conventionally used in South Asian English. In those situations, 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.) Also, provide a conversion to Western numbers for the first instance of each quantity, and provide conversions for subsequent instances if they do not overwhelm the content of the article. For example, write three crore (thirty million). Similarly, if you write 3,00,00,000, also write (30,000,000) or (30000000). (Note that 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, and the choice and order of formats and conversions is a matter of editorial discretion and consensus.)
• When both a figure and spelled-out named number are used in a quantity, it is useful to use a non-breaking space, as in 128 million or 128{{nbsp}}million to prevent a line break from occurring between them.
• Sometimes figures and words may carry different meanings, for example Every number except one implies that there is one exception (we don't know which), while Every number except 1 means that the specific number 1 is the exception.
• Proper names, formal numerical designations, and other idioms comply with common usage; e.g., write Chanel No. 5, 4 Main Street, 1-Naphthylamine, Channel 6, Fourth Amendment, Seventeenth Judicial District, Seven Years' War. This is the case even where it causes a numeral to open a sentence, although this is usually avoided by rewording.

Typography

• Spelled-out two-word numbers from 21 to 99 are hyphenated (e.g. fifty-six), as are fractions (e.g. seven-eighths). Do not hyphenate other multi-word numbers (five hundred, not five-hundred).
• Where a whole number in a percentage is spelled out, the percent sign is not used (three percent or 3%, not three %).
• The ordinal suffix (e.g., th) is not superscripted (23rd and 496th, not 23^rd and 496^th).

Delimiting (grouping of digits)

• Numbers with five or more digits to the left of the decimal point (i.e. 10,000 or more) should be delimited into groups so they can be easily parsed, such as by using a comma (,) every three digits (e.g. 12,200, 255,200, 8,274,527). A full stop (.) should not be used to separate thousands (e.g. 12.200, 255.200) in order to avoid confusion with the decimal point.
• Numbers with four digits to the left of the decimal point may or may not be delimited (e.g. 1250 or 1,250).
• Numbers are not delimited when they are part of mailing and shipping addresses, page numbers, or years with four or fewer digits; years with five or more digits should be delimited (e.g. 10,400 BC).
• In scientific articles, particularly those directed to an expert readership, numbers may be delimited with thin spaces using the {{gaps}} template: {{gaps|8|274|527}} produces 8274527 (note: the thin space character and its HTML entity,  , do not render correctly on some browsers or on screen readers used by visually impaired people).
• Numbers with more than four digits to the right of the decimal point, particularly those in engineering and science where distinctions between different values are important, may be separated (delimited) into groups using the {{val}} template, which uses character-positioning techniques rather than distinct characters to form groups. According to ISO convention (observed by the NIST and the BIPM), it is customary to not leave a single digit at the end, so the last group comprises two, three, or four digits: 1.123, 1.1234, 1.12345, 1.123456, 1.1234567, 1.12345678, 1.123456789, etc. The {{val}} template handles these grouping details automatically; e.g., {{val|1.1234567}} generates 1.1234567 (with a four-digit group at the end), but it can parse no more than a total of 15 significant digits in the significand. For significands longer than this, delimit high-precision values using the {{gaps}} template; e.g., {{gaps|1.234|567|890|123|456}} → 1.234567890123456.
• Constants in mathematics-oriented articles may be grouped in fives; e.g., 3.141592653589793238462643383279....
• The style of delimiting numbers must be consistent throughout an article.

Large numbers

See also: Order of magnitude and Long and short scales

• Large round numbers are generally assumed to be approximations; only where the approximation could be misleading is it necessary to qualify with words such as about.
• Avoid excessively precise values where they are unlikely to be stable or accurate, or where the precision is unnecessary in the context. The sentence The speed of light in a vacuum is 299,792,458 metres per second may well be appropriate since it is precisely that value; The distance from the Earth to the Sun is 149,014,769 kilometres and The population of Cape Town is 2,968,790 people would usually not be, because both values are unstable at that level of precision, and readers are unlikely to care in the context.
• Scientific notation (e.g., 5.8×10⁷ kg) is preferred in scientific contexts; editors can use the {{val}} template, which generates such expressions with the syntax {{val|5.8|e=7|u=kg}}.
• Where values in the millions occur a number of times through an article, upper-case M may be used for million, unspaced, after spelling out the first occurrence (e.g., She bequeathed her fortune of £100 million unequally: her eldest daughter received £70M, her husband £18M, and her three sons £4M each.).
• The named numbers billion and trillion are understood to be short scale, 10⁹ and 10¹² respectively (see Long and short scales). After the first occurrence in an article, billion may be abbreviated to unspaced bn ($35bn). The prefixes giga-, tera-, and larger and their symbols G, T, ... should be limited to computing and scientific contexts.

Fractions

• The template {{frac}} is available for representing common fractions. For p⁄q, type {{frac|p|q}}. For N+p⁄q, type {{frac|N|p|q}}. When copied and pasted, N+p⁄q will appear as N+p/q.
• Unless there is sound reason to the contrary, fractional parts of metric units should be expressed as decimal fractions (5.25 mm), not vulgar fractions (5 ¹/₄ mm). However imperial units may use either form – both (5.25 inches) and (5 ¹/₄ inches) are acceptable, provided that there is consistency in the way that the fractions are represented.
• In mathematics articles (and those on math-heavy fields such as chemistry and astrophysics), fractions should always be written either with a horizontal fraction bar (as in $\textstyle {\frac {1}{2}}$), or with a forward slash and with the baseline of the numbers aligned with the baseline of the surrounding text (as in 1/2). The use of {{frac}} (such as 1⁄2) is discouraged in mathematics articles.
• The use of the few Unicode symbols available for fractions (such as ½) is discouraged entirely, for accessibility reasons among others.
• Use of the ordinal suffix (e.g., th) in fractions expressed in numerals is discouraged (e.g. 1/100, not 1/100th).

Decimal points

• A decimal point is used between the integer and the fractional parts of a decimal; a comma is never used in this role (6.57, not 6,57).
• 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 The response rates were 41 and 47.4 percent, respectively), except if the quantities were measured with different precisions.
• 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.

Percentages

• Percent is commonly used to indicate percentages in the body of an article. The symbol % is more common in scientific or technical articles and in complex listings.
• The symbol is unspaced (71%, not 71 %).
• In tables and infoboxes, the symbol % is normally preferred to the spelled-out percent.
• Ranges should be formatted with one rather than two percentage signifiers (22–28%, not 22%–28%).
• Avoid ambiguity in expressing a change of rates. This can be done by using percentage points, not percentages, to express a change in a percentage or the difference between two percentages; for example, The agent raised the commission by five percentage points, from 10 to 15% (if the 10% commission had instead been raised by 5%, the new rate would have been 10.5%). It is often possible to recast the sentence to avoid the ambiguity (raised the commission from 10% to 15%). Percentage point should not be confused with basis point, which is a hundredth of a percentage point.

Repeating decimals

The preferred way to indicate a repeating decimal is to place a bar over the digits that repeat. To achieve this the template {{overline}} can be used. For example, the markup 14.{{overline|285714}} gives 14.285714.

Consider a short explanation of this notation (called a vinculum) the first time it is used in an article. Some authors place the repeating digits in parentheses rather than using an overbar (perhaps because overbars are not available in their typesetting environment) but this should be avoided in Wikipedia to avoid confusion with expressing uncertainty.

Non-base-10 notations

For numbers expressed in bases other than base ten:

• In computer-related articles, use the C programming language prefixes 0x (zero-ex) for hexadecimal and 0 (zero) for octal. For binary, use 0b. Consider including a note at the top of the page about these prefixes.
• In all other articles, use subscript notation. For example: 137₉, 241₆, 2A9₁₂, A87D₁₆ (use <sub> and </sub>).
• For base eleven and higher, use whatever symbols are conventional for that base. One quite common convention, especially for base 16, is to use upper-case A–F for digits from 10 through 15 (0x5AB3).

Scientific notation, engineering notation, and uncertainty

Notations

• The template {{val}} can be used to facilitate the generation of scientific notation. It is a flexible tool that allows editors great latitude and must have arguments (each section between the vertical bars) properly entered in order for it to generate output that is compliant with formating conventions.
• Scientific notation is done in the format of one leading digit/decimal marker/rest of digits/×10ⁿ, where n is the integer that gives one leading digit.
  • 1.602×10⁻¹⁹ is a proper use of scientific notation.
  • 160.2×10⁻¹⁷ is not a proper use of scientific notation.
• Engineering notation is done in the format of leading digits/decimal marker/rest of digits/×10ⁿ, where n is a multiple of 3. The number of leading digits is adjusted accordingly.
  • 132.23×10⁶ is a proper use of engineering notation.
  • 1.3223×10⁸ is a not proper use of engineering notation.
• It is clearer to avoid mixing scientific notation and engineering notation in the same context (e.g., do not write A 2.23×10² m² region covered by 234.0×10⁶ grains of sand).
• Use discretion when it comes to using scientific and engineering notation. Not all values need to be written in it.
  • Sometimes it is useful to compare values with the same power of 10 (often in tables) and scientific or engineering notation might not be appropriate.

Uncertainty

• Uncertainties can be written in various ways:
  • Value/±/uncertainty/×/10ⁿ/unit symbol (e.g., (1.534±0.35)×10²³ m)
    • Do not group value and uncertainty in parenthesis before the multiplier (e.g., do not write (15.34 ± 0.35) × 10²³ m)
  • Value/superscript positive uncertainty/subscript negative uncertainty/×/10ⁿ/unit symbol (e.g., 15.34+0.43
    −0.23×10²³ m)
  • Value(uncertainty in the last digits)/×/10ⁿ/unit symbol (e.g., 1.604(48)×10⁻⁴ J)
  • Value/±/relative uncertainty(percent)/unit symbol (e.g., 12.34 ± 5% m²)
• The template {{val}} may be used to automatically handle all of this.

Units of measurement

The use of units of measurement is guided by the following principles:

• Avoid ambiguity: Aim to write so you cannot be misunderstood.
• Familiarity: The less readers have to look up definitions, the easier it is to be understood.
• International scope: Wikipedia is not country-specific; apart from some regional or historical topics, use the units in most widespread use worldwide for the type of measurement in question.

In instances where these principles appear to conflict with one another, consult other editors on the article's talk page and try to reach consensus.

Which units to use

Apply these guidelines when choosing the units for the measurements that come first:

• In general, put the units first that are in the most widespread use in the world. Usually, these are International System of Units (SI) units and non-SI units officially accepted for use with the SI; but there are various exceptions for some measurements, such as years for long periods of time or the use of feet in describing the altitude of aircraft.
  • For topics strongly associated with a given place, put the most appropriate units first. For example:
    • US articles generally put United States customary units first.
    • UK articles more often put metric units first, but imperial units may be put first in some contexts. These include:
      • Miles for distances, miles per hour for road speeds and miles per imperial gallon for fuel economy
      • Feet/inches and stones/pounds for personal height and weight measurements
      • Imperial pints for draught beer/cider and bottled milk
      • See also Metrication in the United Kingdom and the style guides of British publications such as that of the Times Online (under "Metric").
    • Articles concerning Commonwealth countries in Africa, Asia and Australasia generally put metric units first.
  • If editors cannot agree on the sequence of units, put the source value first and the converted value second. If the choice of units is arbitrary, use SI units as the main unit, with converted units in round brackets.

How to present the units

• Avoid inconsistent usage. Write a 600-metre (2,000 ft) hill with a 650-metre (2,100 ft) hill, not a 2,000-foot (610 m) hill with a 650-metre (2,100 ft) hill.
• Avoid ambiguous unit names. (See below.)
• Nominal and defined values should be given in the original units first, even if this makes the article inconsistent: for example, When the Republic of Ireland adopted the metric system, the road speed limit in built-up areas was changed from 30 miles per hour (48 km/h) to 50 kilometres per hour (31 mph). (The focus is on the change of units, not on the 3.6% increase.)
• Measurements should be accompanied by a proper citation of the source using a method described at the style guide for citation.
• When the unit put first in the article is not the one given in the source, note the original unit in the citation.

Scientific and technical units

• In scientific articles, use the units employed in the current scientific literature on that topic. This will usually be SI, but not always; for example, natural units are often used in relativistic and quantum physics, and Hubble's constant should be quoted in its most common unit of (km/s)/Mpc rather than its SI unit of s⁻¹.
• Unit symbols that are part of the International System of Units (SI) must rigorously follow the rule of the SI. It is kW for kilowatt and never Kw (uppercase K is the symbol for the Kelvin in the SI and is not the prefix denoting 1000). And it is MHz when one means one-million hertz and never mHz unless one truly means one-thousandth of a hertz. The only exception to this pertains to omitting the space before the percent symbol (as addressed above at "Percentages"). For guidance, see the following Wikipedia articles: "SI prefix", "SI base unit", "SI derived unit", and "SI writing style".
• Some disciplines often use non-SI units or write SI units differently from BIPM-prescribed format. When the reliable sources in a field normally use SI units, articles should do so; when they do not, articles should follow reliable sources. For instance, it is cc in an article on Honda motorcycles engines and not cm³; the term "micron" (rather than micrometre) is also still in widespread use in certain disciplines. Such non-standard units or unit names are always linked on first use.
• Use familiar units rather than obscure units—do not write over the heads of the readership (e.g., a general-interest topic such as black holes would be best served by having mass expressed in solar masses, but it might be appropriate to use Planck units in an article on the mathematics of black hole evaporation); likewise, most articles should use Celsius or Fahrenheit, not the SI kelvin, for ambient temperatures on Earth.

Unit conversions

Where English-speaking countries use different units for the same measurement, follow the "primary" unit with a conversion in parentheses. This enables more readers to understand the measurement. Examples: the Mississippi River is 2,320 miles (3,734 km) long; the Murray River is 2,375 kilometres (1,476 mi) long.

• With imperial units which are not also US customary units, double conversions can be useful: The song's second verse reveals that Rosie weighs 19 stone (266 lb; 121 kg).
• 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, SI units in scientific articles, yards in articles about American football—it can be excessive to provide conversions every time a unit occurs. It could 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 values should use a level of precision similar to that of the source value, so the Moon is 380,000 kilometres (240,000 mi) from Earth, not (236,121 mi). However, small numbers may need to be converted to a greater level of precision where rounding would cause a significant distortion, so one mile (1.6 km), not one mile (2 km).
• Category:Conversion templates can be used to convert and format many common units, including {{convert}}, which includes non-breaking spaces.
• In a direct quotation, always keep the source units.
  • Conversions required for units cited within direct quotations should appear within square brackets in the quote.
  • Alternatively, you can annotate an obscure use of units (e.g. five million board feet of lumber) with a footnote that provides conversion in standard modern units, rather than changing the text of the quotation. See the style guide for citation, footnoting and citing sources.

Avoiding ambiguities

• Identify and define ambiguous units on their first use in an article.
  • Avoid using unit abbreviations that have conflicting meanings in common units systems such as SI and US customary units. Only in the rarest of instances should ambiguous units be used, such as in direct quotations, to preserve the accuracy of the quotation.
    • Use nmi (or NM) to abbreviate nautical mile rather than nm (nanometre).
    • Use kn to abbreviate knot: kt could be confused with kilotonne; kN could be confused with kilonewton.
    • Link such units to their definitions on first use.
  • Some different units share the same name. These examples show the need to be specific.
    • Use nautical mile or statute mile rather than mile in nautical and aeronautical contexts.
    • Use long ton or short ton and not just ton; these units have no symbol or abbreviation and are always spelled out. The tonne, 1000 kilograms, is officially known as the metric ton in the US. Whichever name is used, the symbol is t.
    • Use troy or avoirdupois ounce and not just ounce in articles about precious metals, black powder, and gemstones.
    • Use fluid ounce explicitly to avoid confusion with weight, and specify, if it is Imperial, US or other fluid ounce.
    • Use US gallon or imperial gallon rather than just gallon (also with quarts, pints, and fluid ounces).
    • A calorie (symbol cal) refers to a gram calorie while the kilocalorie (symbol kcal) refers to the kilogram calorie (also known as small calorie and large calorie respectively). When used in a nutrition related article, use the kilocalorie as the primary unit. In US-related articles, use the synonym dietary calorie with a one-time link to kilogram calorie.
  • For bits and bytes, specify whether the binary or decimal meaning of the prefixes kilo (k, K), mega (M), giga (G) and tera (T) is intended. See Quantities of bytes and bits.
• In tables and infoboxes, use unit symbols and abbreviations—do not spell them out.
• It may be appropriate to note that given quantities and conversions are approximate.
  • When part of a full sentence, write approximately in full (e.g., write Earth's radius is approximately 6,400 kilometres, not Earth's radius is approx. 6,400 kilometres or Earth's radius is ~ 6,400 kilometres).
  • In tables, infoboxes, or within brackets, use a tilde (~) or use approx. (e.g. write The capacity of a ship is sometimes expressed in gross register tons, a unit of volume defined as 100 cubic feet (~2.83 m³)).
  • Do not note a conversion as approximate where the initial quantity has already been noted as such, (e.g., write Earth's radius is approximately 6,400 km (4,000 mi), not Earth's radius is approximately 6,400 km (approx. 4,000 mi).

Unnecessary vagueness

Whenever possible, use quantitative rather than vague qualitative descriptions.

Vague	Precise
The wallaby is small.	The average male wallaby is 1.6 metres (63 in) from head to tail.
Prochlorococcus marinus is a tiny cyanobacterium.	The cyanobacterium Prochlorococcus marinus is 0.5 to 0.8 micrometres across.
The large oil spill stretched a long way down the Alaskan coast.	The oil spill that drifted down the Alaskan coast was 3 statute miles (5 km) long and 1,000 feet (300 m) wide.

Unit names and symbols

Conventions

• Where space is limited, such as in tables, infoboxes, and parenthetical notes, and in mathematical formulas, unit symbols are preferable. In prose it is usually better to spell out unit names, but symbols may also be used when a unit (especially one with a very long name) is used many times in an article. However, spell out the first instance of each unit in an article (for example, the typical batch is 250 kilograms ... and then 15 kg of emulsifier is added), except for unit names which are hardly ever spelled out even in publications for general audiences (e.g. the degree Celsius).
• If a unit symbol which can be unfamiliar to a general audience is used in an article, it should be shown parenthetically after the first use of the full unit name: for example, His initial betatron reached energies of 2.3 megaelectronvolts (MeV), while subsequent betatrons achieved 300 MeV.
• Numerical ranges use unspaced en dashes if only one unit symbol is used at the end (e.g. 5.9–6.3 kg), and spaced en dashes if two symbols are used (e.g., 3 μm – 1 mm); ranges in prose can be specified using either unit symbol or unit names, and units can be stated either after both numerical values or after the last (e.g., from 5.9 to 6.3 kilograms, from 5.9 kilograms to 6.3 kilograms, from 5.9 to 6.3 kg and from 5.9 kg to 6.3 kg are all acceptable).
• When dimensions are given, each number should be followed by a unit name or symbol (e.g., write 1 m × 3 m × 6 m, not 1 × 3 × 6 m or 1 × 3 × 6 m³).

Unit names

• Unit names, even those named after people, are common nouns. They are not capitalized when written in full, except where common nouns take a capital. Write The pascal is a unit of pressure, not The Pascal is a unit of pressure. In degree Celsius and degree Fahrenheit, the d is not usually capitalized, but the C and the F are. (The common noun is degree, Celsius being a proper adjective.)
• When unit names are combined by multiplication, separate them with a hyphen or space (e.g., newton-metre or newton metre). The plural is formed by pluralizing the last unit name (e.g., ten newton-metres).
• When unit names are combined by division, separate them with per (e.g., meter per second, not meter/second). The plural is formed by pluralizing the unit preceding the per, since it reads this many units of this per one unit of this (e.g., ten metres per second).
• When they form a compound adjective, values and unit names should be separated by a hyphen: for example, a five-day holiday.

Unit symbols

• Units symbols are preceded by figures, not by spelled-out numbers: for example, 5 min, not five min.
• Values and unit symbols are separated by a non-breaking space. The {{nowrap}} template or the &nbsp; character can be used for this purpose. For example, use 10 m or 29 kg, not 10m or 29kg.
  • Exceptions: Non-alphabetic symbols for degrees, minutes and seconds for angles and coordinates and the percent sign are unspaced (for example, 5° 24′ 21.12″ N for coordinates, 90° for an angle, 47% for a percentage, but 18 °C for a temperature). See also Manual of Style—Geographical Coordinates.
• Write unit symbols in upright roman type. (Italic type is normally reserved for variables and the like.) (e.g., 10 m or 29 kg, not 10 m or 29 kg).
• Standard symbols for units are undotted; e.g., m for the metre (not m.), kg for the kilogram (not kg.), in for the inch (not in., the quotation mark ", or the double prime ″), and ft for foot (not ft., the apostrophe ', or the prime ′).
  • Non-standard abbreviations should be dotted.
• Symbols have no plural form—an s is never appended (e.g., kg, km, in, lb, not kgs, kms, ins, lbs. Write bit, not bits unless bits is used as a word rather than a symbol).
• When unit symbols are combined by multiplication, use a middle dot (·) or a non-breaking space ( ) to separate the symbols. For example, ms is the symbol for the millisecond, while m·s or m s is the symbol for the metre-second.
• When unit symbols are combined by division, use a slash to separate the symbols (e.g., for the metre per second use the symbol m/s, not mps) or use negative exponents (m·s⁻¹). Exceptions include mph for the mile per hour, psi for pounds per square inch, etc.
  • There should be no more than one slash per compound unit symbol (e.g., kg/(m·s), not kg/m/s or kg/m·s).
• Powers of unit symbols are expressed with a superscript exponent (write 5 km², not 5 km^2).
  • A superscript exponent indicates that the unit is raised to a power, not the unit and the quantity (3 metres squared is 9 square metres, or 9 m²).
  • For areas and volumes, squared and cubed US customary or imperial length units may instead be rendered with sq and cu between the number and the unit symbol (e.g., 15 sq mi and 3 cu ft, not 15 mi sq and 3 ft cu).
  • The symbols sq and cu are not used with BIPM-approved unit symbols.
  • Avoid using Unicode superscripts and subscripts (such as ² and ₃). They are harder to read on small displays, and are not aligned with superscript or subscript characters (e.g., x¹x²x₃x₄ vs. x¹x²x₃x₄). Instead, use the <sup></sup> and <sub></sub> tags.

Units and symbols often written incorrectly

• The degree symbol is ° (°);. Using any other symbol (e.g., masculine ordinal º or ring above ˚) for this purpose is incorrect.
• The symbol for the bit is bit, not b. The byte may be represented by either one of the symbols B and byte, but not b or o (French: octet). Unless explicitly stated otherwise, one byte is eight bits (see History of byte).
  • By extension, the symbols for the units of data rate kilobit per second, megabit per second and so on are kbit/s (not kbps or Kbps), Mbit/s (not Mbps or mbps), etc. Similarly, kilobyte per second and megabyte per second are kB/s (not kBps or KBps) and MB/s (not Mbps or MBps).
• The symbols for the degree Celsius, the degree Fahrenheit and the kelvin are °C (not C), °F (not F), and K (not °K) respectively. (C and F are the symbols for the coulomb and the farad respectively; °K is the symbol for the degree Kelvin, the pre-1968 name of the kelvin.) Avoid using the old-fashioned name "degree centigrade" for the degree Celsius, except in quotations and historical contexts.
• The symbols for "kilo-" and smaller prefixes are lower-case (k h da d c m µ n ...), whereas those for "mega-" and larger prefixes are capital (M G T P ...); the symbols for units named after people and optionally that for the liter are capitalized, whereas those for other units are lower-case. For example, kW is the symbol for the kilowatt, not Kw; MHz is the symbol for the megahertz, not mHz (which would be that of the millihertz).
  • For reasons of legibility, use upper-case L for the liter when it is not preceded by a prefix.
  • A capital K can be used for "kilo-" when it means 1024 in computing contexts.
• If you need to express years as a unit, use the symbol a (Latin: annum) along with SI prefixes (e.g., write The half life of thorium-230 is 77 ka and The Cambrian is a geologic period that dates from 540 Ma to 490 Ma).
  • There are many types of years (see year). When years are not used in the layman's meaning (e.g., Julie is 20 years old) clarify which type of year is meant.
• Roman prefixes are not used (M for 10³, MM for 10⁶, B for 10⁹). Use SI prefixes instead.

Quantities of bytes and bits

In quantities of bits and bytes, the prefixes kilo (symbol k or K), mega (M), giga (G), etc. are ambiguous. They may be based on a decimal system (like the standard SI prefixes), meaning 10³, 10⁶, 10⁹, etc., or they may be based on a binary system, meaning 2¹⁰, 2²⁰, 2³⁰, 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 and disk storage.

Follow these recommendations when using these prefixes in Wikipedia articles:

• Specify if the binary or decimal meanings of K, M, G, etc. are intended as the primary meaning. 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, 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 bytes) video card and a 100 GB (100 × 1000³ bytes) hard drive

  A 64 MB (64 × 2²⁰ bytes) video card and a 100 GB (100×10⁹ bytes) hard drive

  A 64 MB (67,108,864 bytes) video card and a 100 GB (100,000,000,000 bytes) hard drive

• Avoid inconsistent combinations such as A 64 MB (67,108,864 bytes) video card and a 100 GB (100 × 1000³ bytes) hard drive. Footnotes, such as those seen in Power Macintosh 5500, may be used for disambiguation.

The IEC prefixes kibi-, mebi-, gibi-, etc. (symbols Ki, Mi, Gi, etc.) are not familiar to most Wikipedia readers (see Complete rewrite of Units of Measurements (June 2008)), so are generally not to be used except under the following circumstances:

• when the article is on a topic where the majority of cited sources use the IEC prefixes,
• when directly quoting a source that uses the IEC prefixes,
• in articles specifically about or explicitly discussing the IEC prefixes.

Adopting suggestions from standards bodies

Wikipedia's style guides do not necessarily conform to the prescriptions of standards bodies (e.g., BIPM and their SI, the IEC, and the ISO).

For instance, SI guidelines regarding the percent symbol (%) are often disregarded in practice: according to the BIPM's SI brochure (subsection 5.3.7), "When [the percent symbol] is used, a space separates the number and the symbol %." This practice has not been well adopted with regard to the % symbol, and per current Wikipedia consensus, is contrary to Wikipedia's Manual of Style. Use 50%, not 50 %.

Wikipedia follows common practice regarding bytes and other data traditionally quantified using binary prefixes (e.g., mega- and kilo-, meaning 2²⁰ and 2¹⁰ respectively) and their unit symbols (e.g., MB and KB). Despite the IEC's 1998 guideline creating several new binary prefixes (e.g., mebi-, kibi-) to distinguish the meaning of the decimal SI prefixes (e.g., mega- and kilo-, meaning 10⁶ and 10³ respectively) from the binary ones, consensus on Wikipedia currently favours the retention of the binary prefixes in computing-related contexts. Use 256 MB of RAM, not 256 MiB of RAM.

Currencies

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

Which one to use

• In country-specific articles, such as Economy of Australia, use the currency of the country.
• In non-country-specific articles such as Wealth, use US dollars ($123), the dominant reserve currency of the world. Some editors also like to provide euro and/or pound sterling equivalents, formatted as described in the next section.

Formatting

• Use the full abbreviation of a currency on its first appearance (e.g. AU$52); subsequent occurrences can use just the symbol of the currency (e.g. $88), unless this would be unclear. The exception to this is in articles related entirely to EU-, UK- or US-related topics, in which the first occurrence may also be shortened (€26, £22 or $34 respectively), unless this would be unclear. When there are different currencies using the same symbol in an article, use the full abbreviation (e.g. US$ for the US dollar and AU$ for the Australian dollar, rather than just $), unless the currency which is meant is clear from the context.
• Do not place a currency symbol after the value (e.g. 123$, 123£, 123€), unless the symbol is normally written as such. Do not write $US123 or $123 (US).
• Currency abbreviations that come before the number are unspaced if they consist of or end in a symbol (£123, €123), and spaced if alphabetic (R 75).
• If there is no common English abbreviation or symbol, use the ISO 4217 standard.
• Format ranges with one, rather than two, currency signifiers ($250–300, not $250–$300).
• Conversions of less familiar currencies may be provided in terms of more familiar currencies, such as the US dollar, euro or pound sterling. Conversions should be in parentheses after the original currency, rounding to avoid excess or false precision (one or two significant digits are usually enough, as the exchange rates can vary significantly) and noting the conversion as approximate, with at least the year given as a rough point of conversion rate reference; e.g., Since 2001 the grant has been 10,000,000 Swedish kronor (approx. US$1.4M, €1.0M, or £800k as of August 2009), not (US$1,390,570, €971,673 or £848,646).
• For obsolete currencies, provide if possible an equivalent, formatted as a conversion, in the modern replacement currency (e.g., decimal pounds for historical pre-decimal pounds-and-shillings figures), or at least a US-dollar equivalent as a default in cases where there is no modern equivalent.
• When possible, always link the first occurrence of lesser-known currencies (146 Mongolian togrogs).
• The names of currencies, currency subdivisions, coins and banknotes should not be capitalised except where normal capitalisation rules require this (for example, at the start of a sentence).
• When called on to use a plural with the euro, use the standard English plurals and not the "legislative" plurals (ten euros and fifty cents, not ten euro and fifty cent). In adjectival use, no plural form is generally used, but rather a hyphenated form: (a two-euro pen, a ten-dollar meal, a ten-cent coin).
• The pound sterling is represented by the £ symbol, with one horizontal bar. The double-barred ₤ symbol is ambiguous, as it has also been used for the Italian lira and other currencies. For non-British currencies that use pounds or a pound symbol (e.g. the Irish pound, IR£) use the symbol conventionally preferred for that currency.

Common mathematical symbols

See also: Manual of Style (mathematics).

• For a negative sign or subtraction operator, use a minus sign (−). You can input a minus sign by either keying in &minus; or by clicking on it in the insert box beneath the edit window (located between the ± and × signs). Do not use an en dash (–), do not use a hyphen (-) unless writing code, and do not use an em dash (—).
• For a multiplication sign, use ×, which can be input by clicking on it in the edit toolbox under the edit window or by keying in &times; (however, the letter x is accepted as a substitute for by in such terms as 4x4).

Common mathematical symbols

Name	Operation	Other use	Symbol	Wikicode	ASCII	Unicode	As binary operator (e.g., 1 + 1)	As unary operator (e.g., +1)
Plus sign	Addition	Positive sign	+	+	+	U+002B	Spaced	Unspaced
Plus or minus	Addition or subtraction	Positive or negative sign	±	±	±	U+00B1	Spaced	Unspaced
Minus or plus	Subtraction or addition	Negative or positive sign	∓	—	∓	U+2213	Spaced	Unspaced
Minus sign	Subtraction	Negative sign	−	−	−	U+2212	Spaced	Unspaced
Multiplication sign, cross	Multiplication, vector product	—	×	×	×	U+00D7	Spaced	—
Division sign, obelus	Division	—	÷	÷	÷	U+00F7	Spaced	—
Equal sign	Equation	—	=	—	=	U+003D	Spaced	—
Not equal sign	Non-equation	—	≠	≠	≠	U+2260	Spaced	—
Approximate sign	Approximation	—	≈	≈	≈	U+2248	Spaced	—
Less than sign	Inequation	—	<	&lt;	&#60;	U+3C	Spaced	—
Less than or equal to	Inequation	—	≤	&le;	&#8804;	U+2264	Spaced	—
Greater than sign	Inequation	—	>	&gt;	&#62;	U+3E	Spaced	—
Greater than or equal to	Inequation	—	≥	&ge;	&#8805;	U+2265	Spaced	—

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. This 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 standardize 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.

Two types of template are available:

• {{coord}}, which has replaced the coor family (and combined their functionality), offers users a choice of display format through user styles, emits a Geo microformat, and is supported by Google Earth.
• Infoboxes such as {{Infobox settlement}}

Depending on the form of the coordinates, the following formats are available.

For just degrees (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, seconds, listed in sequence
• N/S is either N or S, depending on which hemisphere, and
• E/W is either E or W, depending on which hemisphere
• negative values may be used in lieu of S and W

For example:

The city of Oslo, located at 59° 55′ N, 10° 44′ E, enter:

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

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 can control the precision. Trailing zeroes should be included.

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 specification of attributes, such as type, region and scale.

When you have added the coordinates, you might want to 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 variables for coordinates: lat_d, lat_m, lat_s, lat_NS, long_d, long_m, long_s, long_EW.

See also

• For page naming specifics, see Wikipedia:Naming conventions (numbers and dates).
• Wikipedia:Date formattings
• m:Help:Date formatting feature at Meta
• Displaying numbers and numeric expressions

Notes