The formula this calculator uses
Square root
√x = the number which, multiplied by itself, equals x
Example: √144 = 12, because 12 × 12 = 144
Perfect squares vs. irrational roots
Some numbers, like 144, have a whole-number square root — these are called perfect squares. Most numbers don't, and their square roots are irrational, meaning the decimal expansion goes on forever without repeating. This calculator shows the root to several decimal places and also flags whether your number is a perfect square.
How to use this calculator
- Enter a number (zero or positive).
- The square root updates instantly, along with a note if it's a perfect square.
- Decimal values (e.g., 2.25) are also fully supported.
Frequently asked questions
What is a square root?
The square root of a number x is the value that, when multiplied by itself, equals x.
What is a perfect square?
A number whose square root is a whole number, such as 4, 9, 16, 25, or 144.
Can you find the square root of a negative number?
Not as a real number — negative numbers don't have a real square root, which is why this calculator only accepts zero or positive numbers.
How accurate is the decimal result for non-perfect squares?
The result is shown to several decimal places, which is precise enough for virtually all practical purposes.