Tips for LaTeX Math Formatting

How to avoid some of the most common pitfalls leading to ugly LaTeX.

Want to get notified about new posts? Join the mailing list and follow on X/Twitter.

Text Inside of Equations

Use $\textrm{my_variable} = 2$ $\textrm{my_variable} = 2.$

Not $my_variable = 2$ $my_variable = 2.$

Parentheses Around Fractions

Use $\left( \dfrac{1}{2} \right)$ $\left( \dfrac{1}{2} \right).$

Not $( \dfrac{1}{2} )$ $( \dfrac{1}{2} ).$

This applies to brackets, braces, absolute value signs, etc as well.

Exponents and Subscripts

Use $2^{10}$ $2^{10}.$

Not $2^10$ $2^10.$

Vertical Bars

Whenever you want to use a vertical bar $|$ $\vert,$ it has to be in a math environment (e.g. between dollar signs, or in an align environment).

Otherwise, if you try to use it as plain text, it will turn into a horizontal bar: | ———.

Integral Formatting

Use $\displaystyle \int x \, \mathrm{d}x$ $\displaystyle \int_0^1 x \, \mathrm{d}x.$

Not $\int x dx$ $\int_0^1 x dx.$

Evaluating at Bounds

Use $\left. \dfrac{x^2}{2} \right|{12}^{15}$ $\left. \dfrac{x^2}{2} \right\vert_{12}^{15}.$

Not $\frac{x^2}{2} \right|_12^15$ $\frac{x^2}{2} \vert_12^15.$

Arrows Under Limits

Use $\lim\limits_{x \to 0} f(x)$ $\lim\limits_{x \to 0} f(x).$

Not $\lim_{x \to 0} f(x)$ $\lim_{x \to 0} f(x).$

Expectation and Variance

Use $\mathrm{E}[X] \mathrm{Var}[X]$ $\mathrm{E}[X] \, \mathrm{Var}[X].$

Not $E[X] Var[X]$ $E[X] \, Var[X].$

Conditional Probability

Use $P(\textrm{new event} \, | \, \textrm{old event})$ $P(\textrm{new event} \, \vert \, \textrm{old event}).$

Not $P(new event | old event)$ $P(new event \vert old event).$

Multiplication

Use $P(A)P(B), \, P(A) \cdot P(B), \, P(A) \times P(B)$ $P(A)P(B), \, P(A) \cdot P(B), \, P(A) \times P(B).$

Not $P(A) * P(B)$ $P(A) * P(B).$

Align Environments

Whenever you are manipulating an equation, use an align environment:

\begin{align*}
3x+2 &= 5 \\
3x &= 3 \\
x &= 1
\end{align*}

$\begin{align*} 3x+2 &= 5 \\ 3x &= 3 \\ x &= 1 \end{align*}$

Likewise, whenever you are simplifying an expression through multiple steps, use an align environment:

\begin{align*}
\int_1^2 x \, \textrm{d}x &= \left. \dfrac{x^2}{2} \right|_1^2 \\
                          &= \dfrac{2^2}{2} - \dfrac{1^2}{2} \\
                          &= \dfrac{4}{2} - \dfrac{1}{2} \\
                          &= \dfrac{3}{2}
\end{align*}

$\begin{align*} \int_1^2 x \, \textrm{d}x &= \left. \dfrac{x^2}{2} \right|_1^2 \\ &= \dfrac{2^2}{2} - \dfrac{1^2}{2} \\ &= \dfrac{4}{2} - \dfrac{1}{2} \\ &= \dfrac{3}{2} \end{align*}$

Running Off the Page

If a line of math is running off the page, break it after a term midway and put the rest on the next line like this:

\begin{align*}
\int (x + x^2 + x^3 + x^4 + x^5 + x^6) \, \textrm{d}x
      &= \int x \, \textrm{d}x + \int x^2 \, \textrm{d}x + \int x^3 \, \textrm{d}x \\
      &\quad + \int x^4 \, \textrm{d}x + \int x^5 \, \textrm{d}x + \int x^6 \, \textrm{d}x \\
      &\quad + \int x^7 \, \textrm{d}x + \int x^8 \, \textrm{d}x + \int x^9 \, \textrm{d}x
  \end{align*}

$\begin{align*} \int (x + x^2 + x^3 + x^4 + x^5 + x^6) \, \textrm{d}x &= \int x \, \textrm{d}x + \int x^2 \, \textrm{d}x + \int x^3 \, \textrm{d}x \\ &\quad + \int x^4 \, \textrm{d}x + \int x^5 \, \textrm{d}x + \int x^6 \, \textrm{d}x \\ &\quad + \int x^7 \, \textrm{d}x + \int x^8 \, \textrm{d}x + \int x^9 \, \textrm{d}x \end{align*}$

Don’t keep it all on one line. So, don’t do this:

</code>
\begin{align*}
\int (x + x^2 + x^3 + x^4 + x^5 + x^6) \, \textrm{d}x = \int x \, \textrm{d}x + \int x^2 \, \textrm{d}x + \int x^3 \, \textrm{d}x + \int x^4 \, \textrm{d}x + \int x^5 \, \textrm{d}x + \int x^6 \, \textrm{d}x + \int x^7 \, \textrm{d}x + \int x^8 \, \textrm{d}x + \int x^9 \, \textrm{d}x
  \end{align*}
</code>

$\begin{align*} \int (x + x^2 + x^3 + x^4 + x^5 + x^6) \, \textrm{d}x = \int x \, \textrm{d}x + \int x^2 \, \textrm{d}x + \int x^3 \, \textrm{d}x + \int x^4 \, \textrm{d}x + \int x^5 \, \textrm{d}x + \int x^6 \, \textrm{d}x + \int x^7 \, \textrm{d}x + \int x^8 \, \textrm{d}x + \int x^9 \, \textrm{d}x \end{align*}$

Want to get notified about new posts? Join the mailing list and follow on X/Twitter.