Wikipedia:Manual of Style/Superscripts and subscripts

This is an explanatory essay about the various Manual of Style pages linked below.

This page provides additional information about concepts in the page(s) it supplements. This page is not one of Wikipedia's policies or guidelines as it has not been thoroughly vetted by the community.

A superscript or subscript is text that is positioned slightly above or below the normal line of type. Superscripts and subscripts are often rendered in a smaller font size than the adjacent normal text. This part of the Manual of Style aims to achieve consistency in the use and formatting of superscripts and subscripts in Wikipedia articles.

General guidelines

Subscripts and superscripts should be wrapped in  and  HTML tags, respectively, with no other formatting info, with some exceptions (see below). The {{sup}} and {{sub}} templates are useful shortcuts to the HTML markup. Do not use the Unicode subscripts and superscripts ² and ³, or XML/HTML character entity references (² etc.). Rather, write 2 and 3 to produce the superscripts ² and ³. The superscripted 2 and 3 are easier to read, especially on small displays, and ensure that exponents are properly aligned. Compare:

wⁱx²z⁽ⁿ ⁺ ⁶⁾ (Unicode superscripts) to

wⁱx²z^{(n + 6)} (wix2z(n + 6)) or

wⁱx²z^{(n + 6)} (w{{sup|i}}x{{sup|2}}z{{sup|(n + 6)}})

1 + x² + y³ (²) to

1 + x² + y³ (2) or

1 + x² + y³ ({{sup|2}})

These guidelines also apply in citations and template parameters; templates are responsible for cleaning up markup if needed for external consumption, e.g. for COinS.

Exceptions

Phonetic transcriptions

Phonetic transcriptions in the International Phonetic Alphabet and Uralic Phonetic Alphabet (which are most often inside {{IPA}}, {{IPA link}}, {{UPA}}, and related templates) should use Unicode subscripts and superscripts. This follows the recommendation of the International Phonetic Association^[1] and is done by the tools, help pages, and articles referenced in Wikipedia:Manual of Style/Pronunciation. Tone should usually be marked with diacritics or IPA tone symbols, according to Wikipedia:Manual of Style/Pronunciation#Tone. Use {{Needs IPA}} for any non-compliant articles.

Titles

Another exception where Unicode superscripts and subscripts are used is in the title of articles, though this is only rarely necessary. See Wikipedia:Manual of Style/Titles § Typographic effects.

Short descriptions

Per WP:SDFORMAT, {{short description}} cannot use HTML or wikitext formatting, leaving Unicode characters as the only option for superscripts and subscripts.

Dates and numbers

The ordinal suffix (e.g., th) is not superscripted (23rd and 496th, not 23^rd and 496^th).
Centuries and millennia are written using ordinal numbers, without superscripts and without Roman numerals: the second millennium, the 19th century, a 19th-century book (see also Wikipedia:Manual of Style#Numbers as figures or words).
Non-base-10 notations in non-computer-related articles use subscript notation. For example: 137₉, 241₆, 2A9₁₂, A87D₁₆ (use {{sub|radix}} or radix).

Music

In figured bass, superscript and subscript may be combined by using math markup or by using the {{su}} template: <math>C_6^4</math> = $C_{6}^{4}$ , ''C''{{su|b=6|p=4}} = C⁴
₆; (see also Wikipedia:TeX markup or m:Help:Formula).
A superscript circle, or degree sign, which indicates a diminished chord, that may not display correctly for everyone, "°", can be produced by copying and pasting, typing °, or by keying Alt+0176 (Windows PCs). A superscript lower case "^o" ({{sup|o}}) may be used instead. The slashed o, "^ø", which may not display correctly for all readers, is produced by superscripting the character produced by typing ø, or by keying Alt+0248 (Windows PCs). Diminished chords can also be indicated with {{music|dim}} and {{music|dimslash}}.
For inversions and the degree sign superscript and subscript may be done thus: vii{{sup|o}}, I{{sub|6}}. This looks like: vii^o, I₆.

Unit symbols and abbreviations

Powers of unit symbols such as squares and cubes are expressed with a superscript exponent (5 km², 2 cm³). Use the  tag or {{sup}} template rather than the Unicode superscript characters such as ². Squared imperial and US unit abbreviations may be rendered with sq, and cubic with cu (15 sq mi, 3 cu ft).

Science

Chemistry

Descriptions of:

Chemical compounds

C₂H₅OH using {{chem2|C2H5OH}}

Isotopes

³
₂He
using {{Nuclide2|He|3}}

Mathematics

Exponentiation is indicated using a superscript:

2² = 4 using 2{{sup|2}} = 4

Special care is needed with subscripted labels to distinguish the purpose of the subscript (as this is a common error): variables and constants in subscripts should be italic, while textual labels should be in normal text font (Roman, upright). For example:

x_{\text{this one}}=y_{\text{that one}}\,\!

(correct—typeset from <math> x_\text{this one} = y_\text{that one} \,\!</math>),

and

\sum _{i=1}^{n}{y_{i}^{2}}\!

(correct—typeset from <math>\sum_{i=1}^n { y_i^2 }\!</math>),

but not

r=x_{predicted}-x_{observed}

(incorrect—typeset from r = x_{predicted} - x_{observed}).

Moreover, the TeX engine used on Wikipedia may format simple superscripts using ... depending on user preferences. Thus, instead of the image $x^{2}\,$ , many users see x². Formulae formatted without using TeX should use the same syntax to maintain the same appearance.

Notes

^ Esling, John (1999). "Appendix 2: Computer coding of IPA symbols". In International Phonetic Association (ed.). Handbook of the International Phonetic Association: A Guide to the Use of the International Phonetic Alphabet. Cambridge University Press. pp. 161–185. ISBN 0-521-63751-1.

[1] Esling, John (1999). "Appendix 2: Computer coding of IPA symbols". In International Phonetic Association (ed.). Handbook of the International Phonetic Association: A Guide to the Use of the International Phonetic Alphabet. Cambridge University Press. pp. 161–185. ISBN 0-521-63751-1.

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