Why Do Brackets Grow Around a Power in LaTeX?

If parentheses or square brackets become taller when you add a power, the usual cause is automatic delimiter sizing. LaTeX is trying to make the brackets fit the entire expression between \left and \right, including its superscript.

You can keep automatic sizing when it suits the expression, or choose a fixed bracket size for a more consistent appearance. The key is to adjust the delimiter commands without accidentally changing which part of the expression is raised to a power.

Why automatic brackets grow

In math mode, \left and \right ask LaTeX to choose delimiter sizes based on the material between them. For example:

\left( x^2 \right)

The superscript 2 is inside the delimiter pair, so LaTeX takes it into account when sizing the parentheses. The result can look larger than parentheses around plain x.

This behavior is useful for tall expressions such as fractions, sums, and matrices. But automatic sizing is not always visually desirable: a small superscript can cause a noticeable change in bracket height, particularly when nearby expressions use ordinary-sized brackets.

Set the bracket size yourself

Use a matched fixed-size pair when you want to prevent the brackets from growing automatically. For example, \bigl( and \bigr) produce larger-than-normal parentheses, with the same size chosen regardless of the enclosed expression.

Here is a minimal compilable example using the amsmath package:

\documentclass{article}
\usepackage{amsmath}

\begin{document}

Automatic sizing: $\left(x^2\right)$

Fixed sizing: $\bigl(x^2\bigr)$

A taller fixed size: $\Bigl(\dfrac{a}{b}\Bigr)$

\end{document}

The fixed-size delimiter commands come in several levels. Pair the left and right forms at the same level:

Left delimiter	Right delimiter	Typical use
\bigl(	\bigr)	Slightly enlarged
\Bigl(	\Bigr)	Medium size
\biggl(	\biggr)	Larger
\Biggl(	\Biggr)	Largest of these standard sizes

Use the smallest size that comfortably fits the expression. The exact visual result depends on the font and surrounding math, so check the rendered output.

Check where the exponent belongs

The position of the exponent determines what is being raised to a power. Compare these forms:

\bigl(x^2\bigr)

Here the exponent applies to x, which is inside the parentheses. By contrast:

\bigl(x\bigr)^2

Here the exponent applies to the parenthesized quantity. These happen to have the same value for the single term x, but the distinction matters for longer expressions. For instance, (a+b)^2 means the whole sum is squared, while a+b^2 means only b is squared.

If you want the power on the entire parenthesized expression, place the exponent after the closing delimiter. The delimiter pair itself is then sized to fit the expression inside it. If that interior expression is tall, such as a fraction, the parentheses may still need to be tall.

Common mistakes

• Using \left and \right when you want a fixed size. These commands intentionally adapt to the enclosed material. Switch to a matched \bigl/\bigr-style pair for controlled sizing.
• Mixing delimiter levels. Avoid pairs such as \bigl( with \Bigr). Use corresponding left and right commands at the same level.
• Moving the exponent just to change the appearance. This can change the mathematical meaning. Keep the exponent attached to the intended base, then choose the delimiter size separately.
• Using \left without a matching \right. The automatic commands must be paired. For an invisible delimiter on one side, use a dot, as in \left. x \right|.

For most expressions, the practical fix is to replace \left( and \right) with a visually suitable matched pair such as \bigl( and \bigr), then inspect the result in the context of the full equation.