Logarithm Calculator

Calculate common logs, natural logs, and logarithms with any positive base.

Logarithm Calculator helps you compute log base 10, natural log, and log with a custom base. Enter value (x) and base (b), review the breakdown, and use the guidance below to understand what the number means — and what it does not. What the Logarithms calculator does Logarithm Calculator is built for arithmetic, algebra, geometry, and number tools. Compute log base 10, natural log, and log with a custom base. You enter value (x) and base (b), then Simple Calculators computes the result instantly. Results use standard school and engineering formulas that run privately in your browser. How the math works The log of x in base b is the power you raise b to in order to get x. It is worked out as ln(x) ÷ ln(b). The common log uses base 10; the natural log (ln) uses base e ≈ 2.718. The formula: log of x in base b = ln(x) ÷ ln(b). x and b must be positive and b cannot be 1. ln is the natural log (base e ≈ 2.718).