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

Name: Double Arrow Symbol
Availability: InStock
Author: Nham Vu

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

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.

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: 2026-07-22 · Reviewed by Nham Vu