How does the calculator handle any base?

It uses the change-of-base identity, log_base(x) = ln(x) ÷ ln(base). The presets simply set the base to 10, e or 2, while the custom option lets you enter any base greater than 0 and not equal to 1.

How accurate is the result?

It uses double-precision natural logarithms rounded to ten decimals for display, which is exact for typical scientific and engineering use. Logarithms are only defined for x greater than 0 and a base greater than 0 that is not 1.

Is my data sent anywhere?

No. The calculator is privacy-first — the value and base stay in your browser and nothing is sent to any server.

Logarithm Calculator (log, ln, log₂, any base)

Compute log base 10, natural log, log base 2 or any custom base.

Logarithm calculator

Compute a logarithm in base 10 (common log), base e (natural log, ln), base 2, or any custom base. The tool uses the change-of-base identity log_base(x) = ln(x) ÷ ln(base) and confirms the answer by showing the matching power.

It is privacy-first: all of the maths happens locally in your browser, so nothing you enter ever leaves your device.