<sub>: The Subscript element - HTML

`Variable subscripts`

In mathematics, families of variables related to the same concept (such as distances along the same axis) are represented using the same variable name with a subscript following. For example:

html The horizontal coordinates' positions along the X-axis are represented as x₁ … x_n. Result

When writing a chemical formula, such as H₂0, the number of atoms of a given element within the described molecule is represented using a subscripted number; in the case of water, the subscripted "2" indicates that there are two atoms of hydrogen in the molecule.

Another example: html Almost every developer's favorite molecule is C₈H₁₀N₄O₂, which is commonly known as "caffeine." Result

`Technical summary`

Content categories	Flow content, phrasing content, palpable content.
Permitted content	Phrasing content.
Tag omission	None, both the starting and ending tag are mandatory.
Permitted parents	Any element that accepts phrasing content.
Implicit ARIA role	`subscript`
Permitted ARIA roles	Any
DOM interface	`HTMLElement`

`Specifications`

Specification
HTML # the-sub-and-sup-elements

`Browser compatibility`

See also The HTML element that produces superscript. Note that you cannot use sup and sub both at the same time: you need to use MathML to produce both a superscript directly above a subscript next to the chemical symbol of an element, representing its atomic number and its nuclear number. The , , and MathML elements. The CSS vertical-align property. Help improve MDN Was this page helpful to you? Learn how to contribute.This page was last modified on Apr 10, 2025 by MDN contributors. View this page on GitHub • Report a problem with this content