JavaScript (ES2026) reference · Math Methods and Constants

JavaScript Math.sqrt() Method

Return the square root of a number, or NaN for negative numbers. Use it for distances and the Pythagorean theorem.

JavaScript (ES2026) Since ES1

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Syntax

Math.sqrt(x)

Parameter	Description
`x`	A number.

A number or NaN.

Square rootsTry it yourself

console.log(Math.sqrt(16), Math.sqrt(2), Math.sqrt(-1));

Output

4 1.4142135623730951 NaN

Distance between two pointsTry it yourself

const dist = (a, b) => Math.sqrt((a.x - b.x) ** 2 + (a.y - b.y) ** 2);
console.log(dist({ x: 0, y: 0 }, { x: 3, y: 4 }));

Output

Version	Change
JavaScript ES1	Added

Math.cbrt() · Return the cube root of a number; unlike Math.pow(x, 1/3) it works for negative numbers.
Math.hypot() · Return the square root of the sum of squares of its arguments, e.g. the length of a vector or a diagonal.
Math.pow() · Return a base raised to an exponent. The ** operator does the same: Math.pow(2, 10) equals 2 ** 10.
JavaScript Math · tutorial
JavaScript Numbers · tutorial