Square Root Calculator

The Square Root Calculator returns the principal square root of any non-negative number to eight decimal places, and also tells you whether the input is a perfect square. It is handy for geometry homework, engineering checks, statistics (standard deviations involve square roots), and quick mental-math verification.

The perfect-square check is the part people find most useful. A perfect square is a whole number whose root is also a whole number - 4, 9, 16, 25, 36 and so on. The tool flags this instantly, which helps when simplifying radicals in algebra: recognising that 144 is a perfect square means the answer is exactly 12 rather than a decimal approximation. For non-perfect squares such as 2 or 7, the result is an irrational number and the calculator shows its decimal expansion.

Square roots answer the inverse question of squaring: if a room has an area of 45 square metres, sqrt(45) gives the side length of the equivalent square, about 6.708 metres. The same operation underpins the distance formula, the standard deviation formula, and the quadratic formula.

Negative inputs have no real square root, so the tool expects zero or positive numbers. All computation runs locally in your browser.