JavaScript (ES2026) reference · Math Methods and Constants

JavaScript Math.log() Method

Return the natural logarithm (base e) of a number; divide by Math.log(base) to get a logarithm in any base.

JavaScript (ES2026) Since ES1

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Syntax

Math.log(x)

Parameter	Description
`x`	A number.

A number; -Infinity for 0, NaN for negatives.

Natural logarithmTry it yourself

console.log(Math.log(Math.E), Math.log(1), Math.log(0));

Output

1 0 -Infinity

Logarithm in any baseTry it yourself

const logBase = (x, base) => Math.log(x) / Math.log(base);
console.log(logBase(81, 3).toFixed(10));

Output

4.0000000000

Version	Change
JavaScript ES1	Added

Math.log10() · Return the base-10 logarithm of a number, e.g. to count digits or work with decibels.
Math.log2() · Return the base-2 logarithm of a number, e.g. how many bits or how many halvings are needed.
Math.exp() · Return e (about 2.718) raised to the given power, used for exponential growth, decay and probability formulas.
JavaScript Math · tutorial
JavaScript Numbers · tutorial