logarithmClassic tool

Logarithm Calculator

Calculate logarithms from a value, a base and a chosen decimal precision.

This logarithm calculator shows which exponent makes a positive base reach the value you entered. It is useful for study, review, chemistry, exponential growth, programming and quick checks without repeating the math by hand.

Enter the value, the base and the precision you want. The calculation follows log_b(x), where x must be greater than zero and the base must be greater than zero and different from 1. The result also includes an approximate verification line.

When to use this calculator

Use it to solve exercises, compare orders of magnitude or reverse a known power. If you also need the opposite path, try the Power Calculator.

Use base 10 for the common log or 2.718281828 for an approximate natural log.

Use clear inputs to get a more useful result.