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Square Root Symbol (√)

The square root symbol (√), called the radical sign, asks 'what number times itself makes this?' — √9 = 3.

√

Square Root · U+221A · Math Symbols

Click the symbol or the button to copy it, then paste it anywhere — documents, messages, bios and code.

Square Root Symbol codes

Code	Value
Unicode code point	`U+221A`
Unicode name	`Square Root`
HTML named entity	`√`
HTML decimal	`√`
HTML hex	`√`
CSS content code	`\221A`
JavaScript / JSON	`\u221A`
Windows Alt code	`Alt+251`
LaTeX	`\sqrt{}`

Square Root Symbol variants (4)

4 related glyphs — click any tile to copy it. Tiles with a page open that symbol's own page.

∛Cube Root∜Fourth Root⁄Fraction Slash²Superscript Two

Meaning & usage

√ is the radical sign: √x is the number that, multiplied by itself, gives x. The tick of the symbol grew from a handwritten letter r for the Latin 'radix', meaning root, and the bar on top (added later) groups what belongs under the root.

It powers geometry (√2 for a square's diagonal), statistics and physics. Alt+251 types it on Windows; its cube-root sibling is ∛.

Examples in use

√16 = 4
√2 ≈ 1.414
Standard deviation uses √ of the variance

How to type the square root symbol

Windows

Hold the Alt key and type 251 on the numeric keypad (Num Lock on), then release Alt. The code is Alt+251. It also works in Word with the same keys.

Mac

There is no Option-key shortcut for √ on a Mac. Open the Character Viewer with Control+Command+Space, search for "Square Root Symbol", and double-click to insert — or copy it from this page.

iPhone & Android

Most phone keyboards have no built-in key for √. Open this page on your phone, tap Copy, then paste it into your message or bio. (On Android, Gboard's emoji search finds some symbols by name.)

Linux

Press Ctrl+Shift+U, type 221a and press Enter (works in most GTK apps and terminals with IBus). Or copy it from this page.

Frequently asked questions

How do I type √ on Windows and Mac?

On Windows, hold Alt and type 251 on the numeric keypad. On a Mac there is no direct key — copy it here or use Character Viewer (Control+Command+Space).

What is the line on top of the square root symbol called?

The bar is the vinculum. It shows how much of the expression is inside the root: √(a + b) is not the same as √a + b.

How do I write a square root in Word or Google Docs?

Use the equation editor: Insert → Equation, then type \sqrt and press space in Word, or use the equation toolbar in Google Docs. For plain text, copy √ from here and add the number after it.

Why does √ sometimes show as a box or question mark?

The box (called tofu) means the device or font viewing it has no drawing for U+221A (Square Root). The character itself is fine — try a different font or a newer device, or use one of the variants on this page.

Is the Square Root Symbol free to use?

Yes. √ is a standard Unicode text character published in the Unicode Character Database. You may use it in personal and commercial documents, designs and products without permission or payment.