Math.LN10

Updated March 13, 2026 · Math

javascript math constants logarithm

Math.LN10 is a static property of the Math object that holds the natural logarithm of 10 — approximately 2.302585092994046. It is a read-only constant; you cannot change its value.

Syntax

Math.LN10

Value

Math.LN10; // 2.302585092994046

This is equivalent to Math.log(10), but using the constant avoids a function call and is guaranteed to be the same value across all JavaScript engines.

Examples

Accessing the constant

console.log(Math.LN10);
// 2.302585092994046

Converting natural log to log base 10

// log base 10 of x = ln(x) / ln(10)
function log10(x) {
  return Math.log(x) / Math.LN10;
}

console.log(log10(100));
// 2

console.log(log10(1000));
// 3

console.log(log10(1));
// 0

Equivalent to Math.log(10)

Math.LN10 === Math.log(10);
// true (they hold the same value)

Converting between logarithm bases

// General base conversion: log_b(x) = ln(x) / ln(b)
function logBase(x, base) {
  return Math.log(x) / Math.log(base);
}

// Same as log base 10:
logBase(1000, 10); // 3

// Using the constant directly for base 10:
function log10fast(x) {
  return Math.log(x) / Math.LN10;
}

console.log(log10fast(10000));
// 4

Common Patterns

Normalising values on a log scale

const values = [1, 10, 100, 1000, 10000];

const logScaled = values.map(v => Math.log(v) / Math.LN10);
console.log(logScaled);
// [0, 1, 2, 3, 4]

Estimating number of digits

function numberOfDigits(n) {
  if (n === 0) return 1;
  return Math.floor(Math.log(Math.abs(n)) / Math.LN10) + 1;
}

console.log(numberOfDigits(9));       // 1
console.log(numberOfDigits(99));      // 2
console.log(numberOfDigits(12345));   // 5

Working with decibels

// Decibels: dB = 10 * log10(power ratio)
function toDecibels(powerRatio) {
  return 10 * (Math.log(powerRatio) / Math.LN10);
}

console.log(toDecibels(100));
// 20

console.log(toDecibels(1000));
// 30