√Square root symbol
The radical sign. Add an overline for a full square root.
- Unicode
- U+221A
- Alt code
- Alt+8730
- HTML
- √
- Unicode name
- Square Root
Where the Square root symbol comes from
The radical sign is a stylised letter r, for the Latin radix, root. Christoff Rudolff introduced it in 1525; the horizontal bar over the expression came later, from Descartes, and it is what turns the mark from a vague indicator into an unambiguous statement of what is inside the root.
Maths at every level, plus the occasional aesthetic use in bios where it reads as a tick with extra character. In plain text it has a practical weakness: without the overbar there is nothing to show where the root ends.
Square root symbol codes
Tap any value to copy it. All of them produce the same character — they just belong to different places.
How to type √ on any keyboard
Keyboard, code, markup or document — the route to U+221A differs by tool.
Will √ actually show up?
We checked 147 fonts installed on a normal machine and counted how many of them contain this character. A symbol missing from a font is drawn as an empty box — the text is still correct, it just cannot be drawn.
Safe in most places. Common fonts have it. Older or decorative fonts sometimes do not, so a fallback font will kick in.
Symbols people confuse with √
Close enough to be mistaken for it, and still a different code point every time.
Other mathematical symbols
Symbols from the same family, each with its own page: where it came from, how to type it and how well fonts support it.
Math symbols
Operators, set theory, logic, calculus — everything past the number row.