Log base 2, 10, e, custom.. Logarithm Calculator is a free online tool from the ToolsRift Math Calculators collection. It runs entirely in your browser — nothing to install, no signup, and your data never leaves your device.
Enter the number and choose a base — 2, 10, e or a custom value — and the logarithm is calculated instantly.
The logarithm answers 'what exponent gives this number?' — log_b(x) = y means bʸ = x.
log usually means base 10, while ln is the natural logarithm with base e (≈2.71828).
Using the change-of-base formula log_b(x) = ln(x) / ln(b), so any base can be evaluated.