Square Root Calculator
Calculate the square root of a number.
The number that squares to yours
A square root of a number is the value that, multiplied by itself, gives that number — the square root of nine is three, because three times three is nine. This calculates square roots, including for numbers that do not come out neat.
Enter a number to find its square root.
Perfect squares and irrational roots
Some numbers have tidy whole-number roots — the perfect squares like 1, 4, 9, 16 — but most do not, and their roots are irrational: decimals that never end or repeat, like the square root of two. That is not a flaw in the calculation but a genuine property of the number, and the decimal you get is an approximation of an exact value that cannot be written out fully. Square roots come up constantly through the Pythagorean theorem, which needs them to find distances, and in statistics, physics and geometry. The idea also extends: a cube root is the number that cubes to yours, and roots in general undo powers, just as division undoes multiplication.
Common questions
Why is a square root sometimes a never-ending decimal?
Because most numbers are not perfect squares, so their roots are irrational — the decimal never ends or repeats, and what you see is an approximation of an exact value.
What is a square root used for?
Finding distances via the Pythagorean theorem, and throughout statistics, physics and geometry wherever a squared quantity must be undone.
Is anything uploaded?
No. The calculation happens in your browser.