Square Root Calculator
Find the square root of any positive number to ten significant figures, with the cube root and a verification step shown alongside.
How to use it
- Type the number — the square root updates as you type.
- The check line squares the answer back so you can confirm it.
- For other roots, use the nth root calculator instead.
Examples
| √144 | 12 |
| √2 | 1.414213562 |
The square root of a number is the value that, multiplied by itself, gives that number back. √144 = 12 because 12 × 12 = 144. It's one of the most common calculations that turns up outside pure maths — sizing a square area, working out distances with Pythagoras, or finding the standard deviation of a data set, which is itself a square root.
Worked example — sizing a square room
A room needs to hold 20 m² of floor tiles laid out as a square. The side length is √20 ≈ 4.47 m. Builders round that up to the next tile module rather than down, since underestimating leaves a gap.
Perfect squares vs irrational roots
Numbers like 4, 9, 16, 25 and 144 are perfect squares — their square roots are whole numbers. Almost everything else, including √2, √3 and √5, is irrational: the decimal never terminates or repeats, so any answer shown is a rounded approximation, however many digits are displayed.
Questions people ask
Does a positive number have two square roots?
Yes — 144 has roots +12 and −12. By convention the radical symbol means the positive one, which is what is shown here.
Is anything sent to a server?
No. Every calculation runs in your browser, so nothing you type is uploaded and the page keeps working offline once it has loaded.
Last updated 17 August 2026