Logarithm calculator

Solve log_b(x) = y for any missing value, and see ln, log₂ and log₁₀ at a glance.

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How it’s worked out

Rule

Questions people ask

What is a logarithm?

The logarithm answers “what power do I raise the base to, to get this number?” log₁₀(1000) = 3 because 10³ = 1000.

How do I change the base?

log_b(x) = ln(x) ÷ ln(b). Any base works on both sides, as long as it is the same one.