# Math.sqrt()

The Math.sqrt() function returns the square root of a number, that is

$∀x≥0,Math.sqrt(x)=x=the uniquey≥0such thaty2=x\forall x \geq 0, \mathtt{Math.sqrt(x)} = \sqrt{x} = \text{the unique} \; y \geq 0 \; \text{such that} \; y^2 = x$

## Syntax

Math.sqrt(x)

### Parameters

x
A number.

### Return value

The square root of the given number. If the number is negative, NaN is returned.

## Description

If the value of x is negative, Math.sqrt() returns NaN.

Because sqrt() is a static method of Math, you always use it as Math.sqrt(), rather than as a method of a Math object you created (Math is not a constructor).

## Examples

### Using Math.sqrt()

Math.sqrt(9); // 3
Math.sqrt(2); // 1.414213562373095

Math.sqrt(1);  // 1
Math.sqrt(0);  // 0
Math.sqrt(-1); // NaN


## Specifications

Specification Status Comment
ECMAScript 1st Edition (ECMA-262) Standard Initial definition. Implemented in JavaScript 1.0.
ECMAScript 5.1 (ECMA-262)
The definition of 'Math.sqrt' in that specification.
Standard
ECMAScript 2015 (6th Edition, ECMA-262)
The definition of 'Math.sqrt' in that specification.
Standard
ECMAScript 2017 Draft (ECMA-262)
The definition of 'Math.sqrt' in that specification.
Draft

## Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
Basic support (Yes) (Yes) (Yes) (Yes) (Yes)
Feature Android Chrome for Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support (Yes) (Yes) (Yes) (Yes) (Yes) (Yes)