<msub>

Baseline Widely available *

This feature is well established and works across many devices and browser versions. Its been available across browsers since January 2023.

* Some parts of this feature may have varying levels of support.

The <msub> MathML element is used to attach a subscript to an expression.

It uses the following syntax: <msub> base subscript </msub>.

Attributes

This element's attributes include the global MathML attributes as well as the following deprecated attribute:

subscriptshift: A <length-percentage> indicating the minimum amount to shift the baseline of the subscript down.

Note: For the subscriptshift attribute, some browsers may also accept legacy MathML lengths.

html

<math display="block">
  <msub>
    <mi>X</mi>
    <mn>1</mn>
  </msub>
</math>

Implicit ARIA role	None

Specification
MathML Core # subscripts-and-superscripts-msub-msup-msubsup

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This page was last modified on Mar 13, 2025 by MDN contributors.