Left Right Arrow in LaTeX (\leftrightarrow)

Where it is used

Draws a short two-headed arrow, for correspondences, the biconditional, and resonance structures.

Logic uses p \leftrightarrow q for the biconditional connective inside formulas, while \Leftrightarrow and \iff are more common between whole statements. In combinatorics it describes a bijective correspondence between objects, and chemistry uses it between resonance structures, not for equilibrium, which uses \rightleftharpoons. Graph theory may use it for undirected or bidirectional edges. It is a relation and gets thick spacing. For a longer version use \longleftrightarrow. In truth-table discussions it is equivalent to XNOR, true exactly when both sides agree.

Also listed under: Functions & Mapping

Minimal compilable example

Paste this into an empty .tex file and compile it with pdfLaTeX, XeLaTeX or LuaLaTeX.

\documentclass{article}
\begin{document}
Left Right Arrow: $\leftrightarrow$

\[ p \leftrightarrow q \equiv (p \rightarrow q) \land (q \rightarrow p) \]
\end{document}

Related symbols

• Long Left Right Arrow\longleftrightarrow
• Down Arrow (Double)\Downarrow
• Up Down Arrow\updownarrow
• Long Right Arrow (Double)\Longrightarrow
• Left Right Arrow (Double)\Leftrightarrow
• Long Left Arrow (Double)\Longleftarrow

Frequently asked questions

How do I write Left Right Arrow in LaTeX?

Type \leftrightarrow in math mode, for example $p \leftrightarrow q \equiv (p \rightarrow q) \land (q \rightarrow p)$. It works in plain LaTeX without loading any package.

Which package do I need for \leftrightarrow?

None. \leftrightarrow is part of standard LaTeX, so it compiles with nothing in the preamble but the document class.

Can I use \leftrightarrow in text mode, or only in math mode?

Only in math mode. Outside $...$ LaTeX stops with "Missing $ inserted", so write $\leftrightarrow$ in running text. If you only need the glyph in text, paste the Unicode character ↔ instead (with XeLaTeX or LuaLaTeX and a font that has it).