# What is MathML?

Source: https://epubcc.com/glossary/mathml/ (updated 2026-11-04)

MathML is the XML language for mathematical notation, allowed inside EPUB 3 content documents so equations stay text instead of images. Support in reading apps varies.

## Why it matters when you convert a PDF to EPUB

A PDF draws an equation as positioned glyphs and lines, with no record of its structure. Rebuilding MathML from that is hard; a converter that cannot do it reliably should keep the equation's text in order rather than produce wrong mathematics. EPUBCheck asks MathML to carry alternative text (ACC-009).

How EpubCC handles it: the engine does not build MathML. An equation in a PDF comes out as the text characters the PDF contains, which keeps simple formulas readable but loses fraction bars, roots and layout in complex ones; the calculus textbook case shows what that looks like on a real book. A document full of equations is usually better kept as a PDF.