ln
Logarithm Calculator
Calculate logarithms in any base — natural log (ln), log base 10, or custom base.
About This Calculator
Logarithms convert multiplication into addition — the mechanical advantage that made slide rules the primary calculating tool before computers. The Richter scale, pH scale, decibels, and musical intervals are all logarithmic. The natural logarithm appears in the formula for continuous compound interest: A = Pe^(rt).