LaTeX Integral Symbol — \int, \iint, \oint
The integral sign is the backbone of calculus notation. LaTeX provides dedicated commands for single, double, triple, and contour integrals, and handles limit placement automatically in display math.
The Basics
The single integral is \int. Attach bounds with a subscript for the lower limit and a superscript for the upper limit: \int_{a}^{b} f(x) \, \mathrm{d}x. In display math the bounds sit above and below the sign; in inline math they sit to the side unless you add\limits.
For multiple integrals, LaTeX provides \iint (double) and\iiint (triple), both from the amsmath package. For a closed contour integral, use \oint.
Two details matter for publication-quality output. First, write the differential as an upright roman d with a thin space before it: \, \mathrm{d}x, not the italic dx. Second, loadamsmath if you use \iint,\iiint, or \idotsint.
Integral Examples
Indefinite integral
The basic integral. The \, adds a thin space before the upright differential d.
Definite integral
Subscript and superscript set the lower and upper bounds.
Double integral
Requires amsmath. Used for integrals over a 2D region.
Triple integral
Requires amsmath. Used for integrals over a 3D volume.
Contour integral
A closed-loop integral, common in complex analysis.
Integral with limits
\limits forces the bounds above and below the sign even in inline math.
Integral FAQ
How do I write an integral in LaTeX?▼
Use \int for a single integral, \iint for a double integral, and \iiint for a triple integral. Add bounds with subscripts and superscripts: \int_{a}^{b}. The \iint and \iiint commands require the amsmath package.
Why is there a thin space before dx?▼
In rigorous typesetting, the differential is set in an upright roman font and separated from the integrand by a thin space: \, \mathrm{d}x. This follows the ISO convention and is standard in academic publishing.
How do I put integral limits above and below the sign?▼
In display math mode (\[ ... \]), limits automatically appear above and below the integral sign. In inline math mode, add \limits: \int\limits_{a}^{b}.
What package do I need for double and triple integrals?▼
The amsmath package (\usepackage{amsmath}) provides \iint, \iiint, and \idotsint. For contour integrals, \oint is standard, and the esint package offers additional directional variants.