JavaScript (ES2026) reference · Math Methods and Constants

JavaScript Math.floor() Method

Round a number down to the integer below it: Math.floor(4.9) is 4 and Math.floor(-4.1) is -5.

JavaScript (ES2026) Since ES1

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Syntax

Math.floor(x)

Parameter	Description
`x`	A number.

An integer.

Round downTry it yourself

console.log(Math.floor(4.9), Math.floor(-4.1));

Output

4 -5

Format a durationTry it yourself

const seconds = 3725;
console.log(`${Math.floor(seconds / 3600)}h ${Math.floor((seconds % 3600) / 60)}m ${seconds % 60}s`);

Output

1h 2m 5s

Version	Change
JavaScript ES1	Added

Math.ceil() · Round a number up to the next integer: Math.ceil(4.1) is 5 and Math.ceil(-4.1) is -4.
Math.trunc() · Remove the fractional part of a number, rounding towards zero: Math.trunc(-4.7) is -4.
Math.round() · Round a number to the nearest integer; halves round up towards +Infinity, so Math.round(-2.5) is -2.
JavaScript Math · tutorial
JavaScript Numbers · tutorial