Solve for the log, the value, or the base
Switch between finding a logarithm, finding the number a logarithm points to, or finding the base itself — every answer also shows the same number's natural log, common log and binary log for comparison.
How to use
- Choose what you're solving for (the log, the value, or the base)
- Enter the two known numbers (base can be typed as "e")
- Read the result alongside ln, log₁₀ and log₂ of the same number
Common questions
Can I use e as the base?
Yes — type "e" (or E) into the base field in the two modes that ask for one, and it's read as Euler's number. Results are then shown as ln alongside the base-10 and base-2 equivalents for comparison.
Why does it reject a base of 1?
1 raised to any power is always 1, so log base 1 can never reach any other number — there's no consistent answer to give, so the tool flags it rather than returning something misleading.
How does the "find the base" mode actually work?
It rewrites log_b(x) = y as b^y = x, then takes the y-th root of x to isolate b. If no positive base raised to that power reaches x, it says so instead of returning a nonsensical result.