Logarithm Calculator
Compute logarithms in any base — natural log (ln), common log (log₁₀), or a custom base.
About this calculator
The Logarithm Calculator on NumberCals is a free, mobile-friendly tool for anyone needing to compute logarithms in any base — natural log (ln), common log (log₁₀), or a custom base. Enter your values in the form below and the result is computed instantly — no sign-up, no installation, no waiting.
Formula used
log_b(x) = ln(x) / ln(b)
What you'll need
- Value (must be > 0) (e.g. 100)
- Base
- Custom base (only if 'Custom' selected) (e.g. 5)
What you'll get
- Logarithm
Formula
log_b(x) = ln(x) / ln(b)
Result
Frequently Asked Questions
What's a logarithm? +
The inverse of exponentiation. log₁₀(100) = 2 because 10² = 100. log₂(8) = 3 because 2³ = 8.
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