Wikipedia:Manual of Style/Superscripts and subscripts

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A Superscript or a Subscript is text that is positioned slightly above or below the normal line of type and is sometimes rendered in a smaller font. 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[edit]

Subscripts and superscripts should be wrapped in <sub> and <sup> HTML tags, respectively, with no other formatting info. 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 (&sup2; etc). Rather, write <sup>2</sup> and <sup>3</sup> 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) (w<sup>i</sup>x<sup>2</sup>z<sup>(n + 6)</sup>) or
wix2z(n + 6) (w{{sup|i}}x{{sup|2}}z{{sup|(n + 6)}})
1 + x² + y³ (&sup2;) to
1 + x2 + y3 (<sup>2</sup>) or
1 + x2 + y3 ({{sup|2}})

Titles[edit]

One 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.

Dates and numbers[edit]

  • The ordinal suffix (e.g., th) is not superscripted (23rd and 496th, not 23rd and 496th).
  • 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 <sub>radix</sub>).

Music[edit]

  • 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''{{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 typing &deg;, &#176, 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 &oslash;, or &#248;, or by keying Alt+0248 (Windows PCs).
  • For inversions and the degree sign superscript and subscript may be done thus: vii{{sup|o}}, I{{sub|6}}. This looks like: viio, I6.

Unit symbols and abbreviations[edit]

  • Squared and cubic metric-symbols are always expressed with a superscript exponent (5 km2, 2 cm3); squared imperial and US unit abbreviations may be rendered with sq, and cubic with cu (15 sq mi, 3 cu ft).

Science[edit]

Chemistry[edit]

Descriptions of:

C2H5OH using C{{sub|2}}H{{sub|5}}OH
3
2
He
using {{Nuclide2|He|3}}

Mathematics[edit]

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:

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

and

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

but not

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

Moreover, the TeX engine used on Wikipedia may format simple superscripts using <sup>...</sup> depending on user preferences. Thus, instead of the image , many users see x2. Formulae formatted without using TeX should use the same syntax to maintain the same appearance.