What is the difference between ↔ and ⇔?

Both point in two directions, but ↔ (U+2194, Left Right Arrow) is drawn with a single line and is typically used for general bidirectional meaning. ⇔ (U+21D4, Left Right Double Arrow) is drawn with a double line and is the standard math and logic symbol for "if and only if."

What do ⇌ and ⇋ mean?

These are paired harpoon arrows used in chemistry to show a reversible reaction at equilibrium. ⇌ (U+21CC) has the forward harpoon on top; ⇋ (U+21CB) has the reverse harpoon on top. Which one to use depends on which direction you want to emphasize as "forward."

What is the HTML entity for a double arrow?

Use ⇔ or the named entity ⇔ for the left-right double arrow (⇔). The single-line version (↔) uses ↔ or ↔.

How do I type the "if and only if" arrow in LaTeX?

Use \Leftrightarrow for ⇔ in math mode, or \iff for the same symbol with extra spacing around it in a formula. The chemistry equilibrium arrow ⇌ is \rightleftharpoons from the standard LaTeX math symbols.

How do I use a double arrow in CSS?

Set the character as a content value on a pseudo-element, for example content: "\21D4"; on a ::after selector, using the four-digit hex codepoint without the U+ prefix.

What is the URL-encoded form of a double arrow?

The left-right double arrow (⇔) percent-encodes to %E2%87%94 in UTF-8, which is the form used in query strings and encoded URLs.

How do I type a double arrow on Windows or Mac?

In Word or Outlook, type the four-digit hex code (e.g. 21D4) then press Alt + X to convert it. On Mac, open Character Viewer with Control + Command + Space and search "left right arrow" or "harpoon".

Double Arrow Symbol

Click any double-arrow symbol below to copy it, with its Unicode codepoint, HTML entity, CSS content value, URL-encoded form, and keyboard or LaTeX input method.

Click a symbol to copy

Format reference

Symbol	Unicode	HTML Entity	CSS content	URL Encoded
↔	U+2194	↔ (↔)	content: "\2194"	%E2%86%94
⇔	U+21D4	⇔ (⇔)	content: "\21D4"	%E2%87%94
↕	U+2195	↕	content: "\2195"	%E2%86%95
⇕	U+21D5	⇕ (&vArr;)	content: "\21D5"	%E2%87%95
⇄	U+21C4	⇄ (&rlarr;)	content: "\21C4"	%E2%87%84
⇆	U+21C6	⇆ (&lrarr;)	content: "\21C6"	%E2%87%86
⇌	U+21CC	⇌ (&rlhar;)	content: "\21CC"	%E2%87%8C
⇋	U+21CB	⇋ (&lrhar;)	content: "\21CB"	%E2%87%8B
⟺	U+27FA	⟺ (&xhArr;)	content: "\27FA"	%E2%9F%BA

Common usage examples

Logic biconditional ("if and only if")

A ⇔ B means A is true exactly when B is true.

Chemical equilibrium reaction

N₂ + 3H₂ ⇌ 2NH₃

Swap / exchange icon

USD ⇄ EUR

Bidirectional link or toggle label

Home ↔ Dashboard

Keyboard and LaTeX input methods

Windows

In Word or Outlook, type the four-digit hex code (e.g. 21D4) then press Alt + X to convert it. Outside Office, open Character Map and search "left right double arrow".

Mac

Press Control + Command + Space to open Character Viewer, search "left right arrow" or "harpoon", then double-click the symbol.

Linux

Press Ctrl + Shift + U, type 21D4, then press Enter or Space.

LaTeX / math markup

\Leftrightarrow or \iff for ⇔, \leftrightarrow for ↔, and \rightleftharpoons for the equilibrium arrow ⇌.

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Summary

This page lists the Unicode symbols for two-direction and double-line arrows, from the plain two-headed arrow (↔) to the logic biconditional (⇔), the swap arrows (⇄ ⇆) used for exchange or refresh icons, and the harpoon pairs (⇌ ⇋) used for chemical equilibrium. Each entry shows the character, its codepoint, the HTML entity, the CSS content value for a stylesheet, and the percent-encoded form for URLs. Keyboard methods for Windows, Mac, and Linux are included, plus the LaTeX commands used for the math and chemistry variants.

How it works

Browse the grid of double-arrow symbol variants.
Click a symbol card to copy that character to your clipboard.
Open the format row for a symbol to see its Unicode entity, CSS content value, and URL-encoded form.
Follow the keyboard or LaTeX method for your use case to enter the arrow directly.

Use cases

Insert the biconditional (⇔ / "if and only if") into a logic or math proof.
Write the chemical equilibrium arrow (⇌) in a reaction equation.
Use the swap symbol (⇄) as a refresh, exchange, or currency-conversion icon.
Add a bidirectional link or toggle indicator (↔) to a UI label.
Set a CSS content value on a ::before/::after pseudo-element for a two-way marker.
Insert the correct HTML entity for a double arrow in markup.
Look up the URL-encoded form of a double arrow for a query string or href.
Compare the single-line (↔) against double-line (⇔), swap (⇄ ⇆), and harpoon (⇌ ⇋) variants.

Frequently Asked Questions

Last updated: 2026-09-09 · Reviewed by Nham Vu