Logarithm
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The formula, explained
log(x)/log(b)x : Positive numberb : Positive base, other than 1An example to check
Using the starting values below, the calculation gives:
How to use this tool
Check the required inputs: positive number, positive base, other than 1.
Choose the units and options that match your task. Calculate, check the result and use Copy or Print to keep a record. Rounding applies to the display; keep more precision in intermediate steps.
Can I use a decimal comma?
Yes. Numeric fields accept 12.5 or 12,5 and spaces for thousands, such as 1 234.50. Do not mix a point and comma in one number.
Where are my inputs processed?
Calculations run in your browser. Form values are not sent to Analytics. Copying, printing, sharing or opening an external service is your choice.
Method and interface checked on 2026-09-12 · Report an error