Discourse Math

[Discourse]

	Summary	Discourse Math uses MathJax (default) or KaTeX to render maths in your Discourse forum.
	Install Guide	This plugin is bundled with Discourse core. There is no need to install the plugin separately.

As this is an official plugin maintained by the Discourse team, Support, Bug, UX, and Feature requests can be made in the respective categories here on Meta, and tagged with the appropriate plugin tag. Click on a link below to get one started.

 Support  Bug  UX  Feature

Enabling Math

The Math plugin can be enabled from its settings, accessed from your admin/plugins page:

Features

Once enabled, you can render inline math by wrapping with a single $ like so: $E=mc^2$.

You can render blocks of math by wrapping with $$

$$
\sqrt{(-1)} \; 2^3 \; \sum \; \pi
$$

Discourse Math uses a heuristic to ensure that sentences such as: “I spent 20$ and another 100$” do not get converted.

LaTeX Delimiters

When enabled via site settings, you can also use standard LaTeX delimiters:

• Inline: \(...\) - Example: \(E=mc^2\)
• Block: \[...\] - Example:

  \[
  \frac{1}{2}
  \]
  

AsciiMath (MathJax only)

When using MathJax, you can enable asciimath processing which uses % as a delimiter: %E=mc^2%

Composer Integration

The composer includes an Insert Math button in the toolbar with keyboard shortcut Shift+M. This opens a modal where you can:

• Toggle between inline and block mode
• Write your LaTeX expression
• Preview and insert into your post

In the rich text editor, math expressions appear as editable nodes with an edit button to modify the expression.

Chat Support

Math expressions are also rendered in Discourse Chat messages using the same settings and rendering engine.

Rendering Engines

MathJax (Default)

• Version: 4.1
• Output formats: HTML (default) or SVG
• Features:
  • Contextual menu (right-click on math)
  • Accessibility enrichment for screen readers
  • Zoom on alt-click (175% zoom)
  • AsciiMath support

KaTeX (Alternative)

• Features:
  • Fast rendering
  • Mhchem extension for chemical equations
  • CopyTex extension - click math to copy LaTeX source to clipboard
  • Cross-reference support with \label, \ref, and \eqref macros

Site Settings

See all relevant site settings by searching your admin settings for “math”.

Name	Description
discourse math enabled	Enable Discourse Math plugin (adds special processing to $ and $$ blocks)
discourse math provider	Math rendering provider: mathjax (default) or katex
discourse math enable latex delimiters	Enable LaTeX-style delimiters: \(...\) for inline and \[...\] for block math
discourse math mathjax output	MathJax output format: html (default) or svg (MathJax only)
discourse math enable menu	Enable contextual menu for math expressions (MathJax only)
discourse math enable accessibility	Enable accessibility features like text enrichment (MathJax with menu only)
discourse math zoom on click	Zoom 175% on alt-click interaction (MathJax with menu only)
discourse math enable asciimath	Enable asciimath processing with % delimiter (MathJax only)

Hosted by us? This plugin is available on all of our hosting tiers Math | Discourse - Civilized Discussion

Last edited by @sam 2026-01-16T05:05:47Z

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[Ethsim2 (Ethan)]

Just a quick (positive) real-world note after moving to the newer MathJax (v4.1) integration in Discourse Math.

One quality-of-life improvement I’ve noticed is that MathJax now gives very specific, localised feedback when input is invalid or a macro isn’t defined:

• It still renders the surrounding valid structure correctly (e.g. \frac{...}{...}, parentheses, etc.)
• But it leaves the unrecognised command visible literally (e.g. showing \sinc as text) rather than failing the entire expression or producing a confusing partial error.

In practice, this makes it immediately obvious what needs fixing, without obscuring what’s already correct — which is especially helpful in teaching contexts and when iterating on math-heavy posts.

For example, rather than relying on \sinc being defined, the robust approach is to write it explicitly as an operator:

\frac{\Delta}{T}\operatorname{sinc}\!\left(\frac{\omega_r\Delta}{2}\right)

with:

\operatorname{sinc}(x)=\frac{\sin x}{x}

Overall this “render what you can, show the rest clearly” behaviour feels like a big usability win compared to older / less transparent failure modes. Thanks to everyone involved in the MathJax upgrade work.