The LaTeX command for double integral (∬) is \iint (double integral).
\iintWriting a paper? The table generator and the BibTeX cleaner are one click away, no account.
Write \iint inside math mode, that is between $…$ for inline math or in a \[ … \] or equation block for display math. This symbol needs the amsmath package, so add \usepackage{amsmath} to your preamble.
In display math \iint takes its full size; inline it shrinks to fit the line, and \displaystyle forces the large form. With unicode-math under XeLaTeX or LuaLaTeX, typing ∬ in a formula gives the same symbol.
$\iint f(x)$Open this example in the live preview: it renders as you type, with no compiler and no signup.
Calculus and analysis symbols in LaTeX: the full table or search all 350+ LaTeX symbols.
Use \iint in math mode after adding \usepackage{amsmath} to your preamble. For example, $\iint f(x)$.
It comes from the amsmath package: add \usepackage{amsmath} to your preamble.