⇔

Left Right Double Arrow

Unicode
U+21D4
Category
Arrows
HTML Entity
⇔
CSS
\21D4
The Left Right Double Arrow (⇔) is a mathematical and logical symbol primarily used to denote equivalence or mutual implication, often read as "if and only if." Beyond formal logic, it frequently appears in chemistry to represent a reversible reaction, or in general typography to show a strong, two-way relationship between concepts.

How to Type

Windows
Alt+8660 or Win+. then search
macOS
Control+Command+Space then search
Linux
Ctrl+Shift+U 21D4 Space
HTML
⇔ or ⇔

In Programming

In technical documentation and formal logic, this symbol represents the biconditional logical connective (XNOR) or strict equivalence. It is heavily used in LaTeX math environments, where it can be generated using the \Leftrightarrow or \iff commands.

Read full meaning article

Tags

U+21D4 arrow biconditional double double-headed arrow equivalence if and only if iff symbol left right logical equivalence math logic symbol reversible reaction two-way arrow

Related Symbols

← Left Arrow ↑ Up Arrow → Right Arrow ↓ Down Arrow ↔ Left Right Arrow ↕ Up Down Arrow ↖ North West Arrow ↗ North East Arrow ↘ South East Arrow ↙ South West Arrow ↞ Left Two Headed Arrow ↠ Right Two Headed Arrow