Math.round()

The Math.round() function returns the value of a number rounded to the nearest integer.

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 Language Specification (ECMAScript)
# sec-math.round

Browser compatibility

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See also