The Math.round()
function returns the value of a number rounded to the nearest integer.
The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone https://github.com/mdn/interactive-examples and send us a pull request.
Syntax
Math.round(x)
Parameters
x
- A number.
Return value
The value of the given number rounded to the nearest integer.
Description
If the fractional portion of the argument is greater than 0.5, the argument is rounded to the integer with the next higher absolute value. If it is less than 0.5, the argument is rounded to the integer with the lower absolute value. If the fractional portion is exactly 0.5, the argument is rounded to the next integer in the direction of +∞. Note that this differs from many languages' round()
functions, which often round this case to the next integer away from zero, instead giving a different result in the case of negative numbers with a fractional part of exactly 0.5.
Because round()
is a static method of Math
, you always use it as Math.round()
, rather than as a method of a Math
object you created (Math
has no constructor).
Examples
Using round
Math.round( 20.49); // 20 Math.round( 20.5 ); // 21 Math.round( 42 ); // 42 Math.round(-20.5 ); // -20 Math.round(-20.51); // -21
Specifications
Specification |
---|
ECMAScript (ECMA-262) The definition of 'Math.round' in that specification. |
Browser compatibility
The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.
Desktop | Mobile | Server | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
round | Chrome Full support 1 | Edge Full support 12 | Firefox Full support 1 | IE Full support 3 | Opera Full support 3 | Safari Full support 1 | WebView Android Full support 1 | Chrome Android Full support 18 | Firefox Android Full support 4 | Opera Android Full support 10.1 | Safari iOS Full support 1 | Samsung Internet Android Full support 1.0 | nodejs Full support 0.1.100 |
Legend
- Full support
- Full support