How to Type the Infinity Symbol (∞) on a Keyboard

Not on any standard key — here’s the fastest method on every platform

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The infinity symbol ∞ (Unicode U+221E) appears in mathematics, physics, philosophy, design, and plenty of casual contexts — tattoo descriptions, social media, creative writing.

It’s not on any keyboard but every platform has a reliable method to produce it, and on most of them the fastest approach takes under two seconds once you know it.

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Windows

Method 1: Alt Code

Hold Alt and type 236 on the numeric keypad. Release Alt and ∞ appears.

• Num Lock must be on
• Use the numeric keypad only — not the number row at the top
• Doesn’t work on laptops without a dedicated numpad

Method 2: Character Map

Search for Character Map in the Start menu. Find ∞ in the Mathematical Operators block, copy it, and paste. Works on any Windows machine including those without a numpad.

Method 3: System-Wide Text Expansion

Use PhraseExpress, AutoHotkey, or Espanso to map a trigger like inf or \inf to ∞ system-wide. Works in every application without remembering Alt codes.

A simple AutoHotkey script:

::inf::∞

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Mac

Method 1: Keyboard Shortcut

Press Option + 5 to type ∞ instantly.

This is the method to remember on Mac. Works in every application with no setup required — browsers, documents, email, everything.

Method 2: Character Viewer

Press Control + Command + Space to open the Character Viewer. Search “infinity” and double-click ∞ to insert.

Method 3: Text Replacement

Go to System Settings → Keyboard → Text Replacements and map a trigger like inf or \inf to ∞. Works system-wide across every Mac app.

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iPhone and iPad

Method 1: Text Replacement

Go to Settings → General → Keyboard → Text Replacement. Add ∞ as the phrase and a trigger like inf or \inf as the shortcut. Auto-expands in any text field across iOS after setup.

The standard iOS keyboard doesn’t have ∞ on a long press, so text replacement is the most practical method for regular use.

Method 2: Copy and Keep It Accessible

Type ∞ once using another method, copy it, and save it somewhere accessible — a note, a pinned message — to paste when needed on iOS. For occasional use this is faster than setting up a replacement.

Method 3: Symbols Page

Tap ?123 then #+— to reach the extended symbols page. ∞ may appear on one of the secondary symbol screens depending on your iOS version and keyboard configuration.

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Android

Method 1: Gboard Symbol Search

In Gboard, tap the G logo and use the search function. Type “infinity” and ∞ appears as an insertable option. Tap to insert.

This is the fastest method on Android for occasional use — no setup required.

Method 2: Symbol Keyboard

Tap ?123 to switch to numbers and symbols, then look for ∞ on the symbols pages. On some keyboards it’s accessible directly without a search.

Method 3: Text Replacement

In Gboard settings, go to Dictionary → Personal Dictionary, select your language, and add ∞ with a shortcut like inf. Expands automatically as you type for regular use.

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Chromebook

Method 1: Unicode Input

Press Ctrl + Shift + U, type 221e, then press Enter or Space. ∞ appears at your cursor immediately.

Method 2: Special Characters Picker

Press Search + Shift + Space to open the emoji and special characters panel. Search “infinity” and select ∞.

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Linux

Method 1: Unicode Input

Press Ctrl + Shift + U, type 221e, then press Enter. Works consistently across most Linux distributions.

Method 2: Compose Key

With a Compose key configured, some distributions support Compose + i + n + f or similar sequences for ∞. Check your specific compose key table as sequences vary by distribution.

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Microsoft Word (Any Platform)

Method 1: Alt + X

Type 221E then immediately press Alt + X. Word converts the Unicode code point to ∞ instantly.

Method 2: Insert Symbol With AutoCorrect

Go to Insert → Symbol → More Symbols. Select Mathematical Operators from the character set dropdown or search by name. Find ∞, click Insert, and click AutoCorrect to set up a trigger like \inf that Word converts automatically as you type.

Method 3: Equation Editor

For mathematical documents where ∞ appears in formal equations, press Alt + = to open an equation field and type \infty followed by Space. Word’s equation editor renders it as a properly formatted ∞ in math mode.

Method 4: Alt Code

Hold Alt and type 236 on the numpad — same as the standard Windows method.

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Google Docs

Option + 5 on Mac works inside Google Docs exactly as it does everywhere else. The Alt code works on Windows inside Docs.

For equations, go to Insert → Equation and type \infty followed by Space — Google’s equation editor renders it correctly in math formatting.

Go to Insert → Special Characters, search “infinity,” and click to insert for occasional use without remembering shortcuts.

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LaTeX

In LaTeX, ∞ is typed as \infty in math mode:

latex

As $x \to \infty$, the function approaches zero.

No Unicode input needed — LaTeX’s math mode handles it through the standard command.

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HTML and Web Development

In HTML, ∞ can be inserted several ways:

html

<!-- HTML entity name -->
&infin;

<!-- HTML entity number -->
&#8734;

<!-- Unicode hex reference -->
&#x221E;

<!-- Direct Unicode character -->
∞

All four produce the same result in a browser. The named entity ∞ is the most readable in source code.

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Programming and Code

In most programming contexts, ∞ is better represented through language constructs than the Unicode character.

• Python: float('inf') or math.inf
• JavaScript: Infinity or Number.POSITIVE_INFINITY
• Java: Double.POSITIVE_INFINITY
• C/C++: INFINITY from <math.h> or std::numeric_limits<double>::infinity()

Using the Unicode character ∞ in code is fine for string literals and comments but shouldn’t be used as a mathematical value in calculations — use the language’s built-in infinity representation instead.

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Quick Reference Table

Platform	Fastest Method	Shortcut
Windows	Alt code (numpad)	Alt + 236
Mac	Keyboard shortcut	Option + 5
iPhone / iPad	Text replacement	Set inf → ∞ in settings
Android	Gboard symbol search	Search “infinity” in G menu
Chromebook	Unicode input	Ctrl + Shift + U, 221e
Linux	Unicode input	Ctrl + Shift + U, 221e
Microsoft Word	Code conversion	Type 221E then Alt + X
LaTeX	Math command	\infty in math mode
HTML	Named entity	∞

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The Bottom Line

On Mac, Option + 5 is the fastest and most memorable method — no setup, works everywhere, done in a single keystroke combination. On Android, Gboard’s symbol search finds it instantly without any prior configuration. On Windows, Alt + 236 on the numpad covers most situations reliably.

For anyone writing mathematical content regularly — in Word, LaTeX, or Google Docs — the equation editor approach using \infty is worth knowing because it produces properly formatted math-mode output rather than an inline Unicode character.

A text expander shortcut mapping inf to ∞ is the two-minute investment that pays off for anyone who uses the symbol with any regularity — it works system-wide and makes ∞ as easy to type as any letter.

Option + 5 on Mac. Alt + 236 on Windows. Gboard search on Android. \infty in LaTeX. Pick the one for your platform and ∞ is always a shortcut away.