Aligning equations in LaTeX

5 min read Intermediate

The amsmath package provides the align environment for aligning multiple equations at a common point (typically the = sign). Use & to mark the alignment point.

The align environment

LaTeX

\begin{align}
    x + y &= 5 \\
    2x - y &= 1
\end{align}

% Sans numérotation : align*
\begin{align*}
    (a + b)^2 &= a^2 + 2ab + b^2 \\
    (a - b)^2 &= a^2 - 2ab + b^2
\end{align*}

Multi-line calculation

To develop a calculation step by step, align on the = sign:

LaTeX

\begin{align*}
    f(x) &= (x+1)(x-2) \\
         &= x^2 - 2x + x - 2 \\
         &= x^2 - x - 2
\end{align*}

Centered equations with gather

If you simply want to center multiple equations without aligning them, use gather:

LaTeX

\begin{gather*}
    E = mc^2 \\
    F = ma \\
    PV = nRT
\end{gather*}

Warning Do not use eqnarray, which is obsolete. Always prefer align from the amsmath package, which handles spacing better.

Test your knowledge

3 questions to check what you have learned.

Which environment aligns several equations on the equals sign?

The align environment from the amsmath package is the recommended choice. eqnarray is obsolete and handles spacing poorly.

Which character marks the alignment point in align?

You place the ampersand & just before the alignment sign, e.g. &=, and end each line with \\.

Which environment centers several equations without aligning them to each other?

gather (and its unnumbered version gather*) centers each equation. To align them to each other, use align instead.

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The align environment

Multi-line calculation

Centered equations with gather

Test your knowledge

Related guides

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