\frac - LaTeX fraction command

\frac{a}{b}

Renderer support

Package	MathJax	KaTeX	XeTeX
`ams`	MathJax: Full	KaTeX: Full	XeTeX: Full
`base`	MathJax: Full	KaTeX: Full	XeTeX: Full

Syntax#

\fracm{a}math contentm{b}math content

Argspec m m — two mandatory arguments. Same argspec in ams and base. Reading argspecs

Use \dfrac when the fraction should stay display-sized.

\dfrac{a}{b}

\tfrac{a}{b}

\frac{1+\frac{a}{b}}{1-\frac{a}{b}}

\frac{dy}{dx}

base

\frac12

Package	Signature	Allowed mode	Notes
`ams`	`m m`	math	Standard fractions in mathematical expressions, derivations, and formulas.
`base`	`m m`	math	Used for fractions in mathematical expressions and derivations

TeXForm parses this entry as prefix syntax; the package determines its argument specification.

\genfrac{}{}{}{}{#1}{#2}exact
This is the AMS mapping's fixed-parameter specialization of \genfrac with empty delimiters, empty thickness, and empty style.
a \over bapproximate
\over is an infix primitive with different grouping scope; \frac is preferred in LaTeX
{a \over b}exact
Primitive infix form (discouraged in modern LaTeX)
\dfrac{a}{b}approximate
Forces display style

`ams`
Input	Case	MathJax	KaTeX	XeTeX
`\frac{a}{b}`	Positive · baseline	Pass	Pass	Pass
`\frac a{b}`	Positive · bare[0]	Pass	Pass	Pass
`\frac{a}b`	Positive · bare[1]	Pass	Pass	Pass

`base`
Input	Case	MathJax	KaTeX	XeTeX
`\frac{a}{b}`	Positive · baseline	Pass	Pass	Pass
`\frac a{b}`	Positive · bare[0]	Pass	Pass	Pass
`\frac{a}b`	Positive · bare[1]	Pass	Pass	Pass