Writing fractions in LaTeX

The \frac command is the main tool for writing fractions in LaTeX. This guide covers simple fractions, display variants, and nested fractions.

Simple fraction with \frac

The basic syntax is \frac{numerator}{denominator}. The fraction automatically adapts to the context (inline or display mode).

La probabilité est $\frac{1}{6}$ pour chaque face.

En mode display :
\[
    \frac{a}{b} + \frac{c}{d} = \frac{ad + bc}{bd}
\]

Controlling size: \dfrac and \tfrac

By default, \frac reduces size in inline mode. Use \dfrac to force display size, or \tfrac to force the smaller inline size even in display mode.

% Comparaison en ligne :
Avec frac : $\frac{1}{2}$ \quad
Avec dfrac : $\dfrac{1}{2}$ \quad
Avec tfrac : $\tfrac{1}{2}$

% En mode display, tfrac est compact :
\[
    \tfrac{1}{2} + \tfrac{1}{3} = \tfrac{5}{6}
\]

Nested and continued fractions

You can nest \frac as needed. For continued fractions, use \cfrac which maintains a readable size at each level.

% Fraction imbriquée
\[
    \frac{1}{1 + \frac{1}{2}} = \frac{2}{3}
\]

% Fraction continue avec cfrac
\[
    \sqrt{2} = 1 + \cfrac{1}{2 + \cfrac{1}{2 + \cfrac{1}{2 + \cdots}}}
\]

Reference table