How to type the square root symbol (√) on Windows
To type the square root symbol on Windows, hold Alt and type 251 on the numeric keypad. This code comes from the classic PC character set and works in Notepad, Word and most apps. In Word you can also type 221A and press Alt + X.
Quick answer
Hold Alt, type 251 on the numeric keypad, release: √.
Step by step
Turn on Num Lock
Use the keypad on the right of the keyboard, with Num Lock on.
Hold Alt and type 251
Keep Alt down while you type 2, 5, 1 on the keypad.
Release Alt
The radical sign √ appears.
No leading zero this time
Unlike many symbols, √ has only the short alt code. It exists in code page 437 (the original IBM PC set, position 251) but not in Windows-1252, so Alt + 0251 gives the letter û instead. If you see û, drop the zero. The alt code chart shows both columns side by side.
Better square roots in Word
A typed √ is fine for text such as “√2 ≈ 1.414”. For a proper root with a bar over the number, use Word’s equation editor: press Alt + =, type \sqrt, a space, then the number in brackets, or pick the radical template on the Equation ribbon. For the plain character, 221A followed by Alt + X is quickest.
On a laptop
Without a numeric keypad, alt codes will not work from the number row. Press Win + ., open the Symbols tab (Ω) and choose √ from the maths group, or search Character Map for “square root”.
Cube and fourth roots
Unicode also has ∛ (cube root, U+221B) and ∜ (fourth root, U+221C). They have no alt codes; type 221B or 221C and press Alt + X in Word, or copy them from the cube root page. In Excel, remember that =SQRT() calculates a root while √ is only a label. The square root symbol page lists the HTML entity √ and all other codes, and the Windows symbols guide covers the rest of the maths set.
Frequently asked questions
What is the alt code for the square root symbol?
Alt + 251 on the numeric keypad. Do not add a leading zero: Alt + 0251 gives û.
How do I insert a square root in Word?
Type 221A and press Alt + X for the √ character, or use the equation editor (Alt + =) for a root with a bar over the number.
Is √ the same as a check mark?
No. It looks similar, but √ is a maths sign. For ticks use ✓ (U+2713).