Equilibrium Arrow in LaTeX (\rightleftharpoons)

Where it is used

Pair of opposing half-arrows (harpoons) showing a chemical reaction at dynamic equilibrium.

IUPAC recommends harpoons for equilibrium, as in N_2 + 3H_2 \rightleftharpoons 2NH_3, while two full arrows indicate a reversible process in general. The top harpoon points right, matching the forward reaction. Its mirror is \leftrightharpoons, with the leftward harpoon on top. It is a relation, so TeX spaces it like =. To print conditions above the arrow, such as a catalyst, you can use \overset{\text{Fe}}{\rightleftharpoons}, though dedicated chemistry tools give longer arrows. In physics the same symbol sometimes denotes a two-way correspondence.

Minimal compilable example

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

\documentclass{article}
\usepackage{amsmath}
\begin{document}
Equilibrium Arrow: $\rightleftharpoons$

\[ \text{N}_2 + 3\text{H}_2 \rightleftharpoons 2\text{NH}_3 \]
\end{document}

Related symbols

• Reversible Reaction\leftrightarrows
• Right Arrow\rightarrow
• Long Right Arrow\longrightarrow
• Up Arrow\uparrow
• Down Arrow\downarrow
• Isotope{}^{14}_{6}\text{C}

Frequently asked questions

How do I write Equilibrium Arrow in LaTeX?

Type \rightleftharpoons in math mode, for example $\text{N}_2 + 3\text{H}_2 \rightleftharpoons 2\text{NH}_3$. It works in plain LaTeX without loading any package.

Which package do I need for \rightleftharpoons?

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

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

Only in math mode. Outside $...$ LaTeX stops with "Missing $ inserted", so write $\rightleftharpoons$ 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).