Math Mode in LaTeX

LaTeX typesets formulas only in math mode. Put a formula inside a sentence between $ … $ or $ … $ (inline), on its own centered line between \[ … \] (display), or in \begin{equation} … \end{equation} to give it a number. Inside math mode spaces are ignored and letters are italic; use \text{…} for words.

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Ways into math mode

$ a^2 + b^2 $
$a^{2} + b^{2}$
Inline math, the LaTeX form.
$ a^2 + b^2 $
$a^{2} + b^{2}$
Inline math, the TeX form; same result.
\[ a^2 + b^2 = c^2 \]
$a^{2} + b^{2} = c^{2}$
Displayed on its own line, not numbered.
\begin{equation} E = mc^2 \end{equation}
$\begin{matrix} (1) & E = m c^{2} \end{matrix}$
Displayed and numbered.
\begin{equation*} … \end{equation*}
Text mode, no math preview
Displayed, not numbered (amsmath).
\text{for all } x
$for all x$
Upright words with normal spacing inside a formula (amsmath).
\label{eq:energy} … \eqref{eq:energy}
Text mode, no math preview
Name an equation, then refer to it as (1).
x = 1 \tag{A}
$\begin{matrix} (A) & x = 1 \end{matrix}$
Custom equation tag instead of a number.
\displaystyle \sum_{i=1}^{n} i
$\sum_{i = 1}^{n} i$
Force display size inside inline math.

Try it live

Change the formula and the preview redraws as you type. Copy the LaTeX, download a PNG or SVG, copy it for Word, or use Edit here on any example below to load it.

LaTeX

Templates

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Math mode and equations examples

Each result below is drawn from the LaTeX under it. Copy the code, edit it on this page, or open it in the full editor.

Words inside a formula

f (x) = {\begin{cases} 1 & if x > 0 \\ 0 & otherwise \end{cases}

LaTeX

f(x) = \begin{cases} 1 & \text{if } x > 0 \\ 0 & \text{otherwise} \end{cases}

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Spacing commands
$a b a b a b a b$
LaTeX
```
a\,b \quad a\;b \quad a\quad b \quad a\qquad b
```
\, thin, \; thick, \quad and \qquad wide. Plain spaces do nothing in math.
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Inline vs display size
$\sum_{k = 1}^{n} \frac{1}{k} \sum_{k = 1}^{n} \frac{1}{k}$
LaTeX
```
\textstyle \sum_{k=1}^{n} \frac{1}{k} \quad \displaystyle \sum_{k=1}^{n} \frac{1}{k}
```
Inline math shrinks fractions and puts limits beside the sum.
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Numbered equation with a custom tag
$\begin{matrix} (Gauss) & \nabla \cdot E = \frac{ρ}{ε_{0}} \end{matrix}$
LaTeX
```
\nabla \cdot \mathbf{E} = \frac{\rho}{\varepsilon_0} \tag{Gauss}
```
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Units in text
$v = 12 m/s$
LaTeX
```
v = 12\ \text{m/s}
```
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Upright function names
$\sin^{2} θ + \cos^{2} θ = 1$
LaTeX
```
\sin^2 \theta + \cos^2 \theta = 1
```
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In a LaTeX document

These commands work in the text of a .tex document (Overleaf, TeX Live, MiKTeX), not inside math. The box on the right shows what the compiled PDF looks like.

Inline and displayed math in a paragraph

LaTeX

The roots of \(ax^2 + bx + c = 0\) are
\[
  x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}.
\]

Numbered equation and a reference

LaTeX

\usepackage{amsmath}  % preamble

\begin{equation}
  E = mc^2 \label{eq:energy}
\end{equation}
Equation \eqref{eq:energy} relates mass and energy.

The equation gets the number (1) at the right margin, and \eqref prints "(1)" in the sentence.

Inline or display

Inline math ($ … $ or $ … $ ) sits in the line of text and is set compactly: fractions shrink and sum limits move to the side. Displayed math (\[ … \]) gets its own centered line at full size. Use display for anything taller than a line or worth referring to.

Avoid $$ … $$ in LaTeX documents: it is plain-TeX syntax that gives inconsistent spacing and ignores the fleqn option. \[ … \] does the same job correctly. (In Markdown editors $$ is the normal display syntax.)

Numbering and referring to equations

equation numbers one displayed formula; equation* (amsmath) is the same without the number. For several aligned lines use align or align* — see the multiline equations page.

Put \label{eq:name} inside the environment and refer to it with \eqref{eq:name}, which prints the number in parentheses, or \ref{eq:name} for the bare number. Run LaTeX twice (Overleaf does this for you) so the numbers resolve instead of showing ??.

Text inside math

Math mode ignores spaces and sets letters as italic variables, so words typed directly look wrong. \text{…} (amsmath) switches to normal text that follows the surrounding size, including in subscripts. Add the spaces you need inside the braces: \text{ if }.

Common mistakes

^ and _ only exist in math mode. In text LaTeX stops with "Missing $ inserted".
Instead of
```
The area is x^2.
```
Write
```
The area is $x^2$.
```
Letters in math mode are variables: "if" is set as italic i times f and the space disappears.
Instead of
```
$if x > 0$
```
Write
```
$\text{if } x > 0$
```
A blank line inside display math is an error; one equation holds one line. Use align for several.
Instead of
```
\begin{equation}
  a = b

  c = d
\end{equation}
```
Write
```
\begin{align}
  a &= b \\
  c &= d
\end{align}
```
$$ is plain TeX; \[ … \] is the LaTeX form with correct spacing.
Instead of
```
$$ E = mc^2 $$
```
Write
```
\[ E = mc^2 \]
```

In Overleaf, MathJax and Word

Overleaf and pdfLaTeX
All forms work; equation*, align and \text need \usepackage{amsmath}, which Overleaf templates normally include. Unresolved references show as ?? until the next compile.
MathJax and KaTeX
MathJax recognizes $ … $, \[ … \] and $$ … $$ by default; single $ for inline math has to be switched on in its configuration. Equation numbers need its tags option. Markdown apps such as Obsidian, Jupyter and GitHub use $ … $ and $$ … $$.
Microsoft Word
In Word, Alt+= (Windows) inserts an equation box — that is Word's math mode. To reuse LaTeX, build the formula in the editor on this page and use Copy for Word to paste an editable equation.

Math mode and equations in LaTeX: questions

How do I enter math mode in LaTeX?: Use $ … $ or $ … $ for a formula inside a sentence and \[ … \] for one on its own line. Environments such as equation and align are math mode too.
How do I write normal text inside an equation?: Wrap it in \text{…} (amsmath): x > 0 \text{ for all } t. Include the spaces inside the braces.
What is the difference between $ and \[ in LaTeX?: $ … $ is inline math within the line of text; \[ … \] is displayed math on its own centered line at full size.
How do I number an equation and refer to it?: Use \begin{equation} … \label{eq:x} \end{equation} and write \eqref{eq:x} in the text; it prints the number, e.g. (1).
How do I stop an equation from being numbered?: Use \[ … \] or equation*. In align, add \notag to a line to drop its number.

Related LaTeX reference

Have the formula as a picture?

Paste a screenshot or photo of the equation and get its LaTeX, ready to copy or open in the editor.

Convert an image to LaTeX

Math Mode in LaTeX

Ways into math mode

Try it live

Math mode and equations examples

Words inside a formula

Spacing commands

Inline vs display size

Numbered equation with a custom tag

Units in text

Upright function names

In a LaTeX document

Inline and displayed math in a paragraph

Numbered equation and a reference

Inline or display

Numbering and referring to equations

Text inside math

Common mistakes

In Overleaf, MathJax and Word

Overleaf and pdfLaTeX

MathJax and KaTeX

Microsoft Word

Math mode and equations in LaTeX: questions

Related LaTeX reference

Have the formula as a picture?