Log Calculator
Calculate the logarithm of a number to any base, along with its natural log (ln) and log base 10.
Show solution steps
What is the Log Calculator?
A logarithm answers the question "what power must the base be raised to, in order to get this number?" Logarithms appear throughout science and everyday measurement scales — the pH scale for acidity, the Richter scale for earthquake magnitude, and decibels for sound are all logarithmic — and in finance, logs are used to work out how long an investment takes to double at a given growth rate.
How to Calculate
Enter the number and the base you want the logarithm in — common choices are base 10 (log) and base e (natural log, ln). Any base can be computed via the change-of-base formula, logₐ(x) = ln(x) ÷ ln(a), which is what the calculator uses internally regardless of which base you ask for.
Formula
logₐ(x) = ln(x) ÷ ln(a)
How to Use
- Enter your details in the fields above.
- The result updates instantly as you type.
- Use Copy, Print or Download PDF to save your result.