Logarithm Calculator
Logarithm of a number in any base, plus natural and base-10 logs.
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Step by step
The formula
log_b(x) = ln(x) / ln(b)
A logarithm is the inverse of raising to a power: it answers “what exponent turns the base into this number?” Any base can be computed from natural logs via the change-of-base rule, which is exactly what this tool does.
All calculations run locally in your browser and update instantly as you type.
Example calculations
Common questions this calculator answers — select one to load its values.
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Frequently asked questions
What is a logarithm?+
A logarithm answers "to what power must the base be raised to get this number?" For example log₁₀(1000) = 3.
All calculations run locally in your browser. Nothing you type is sent to a server.