Compute the logarithm of a number in any base, with natural log (ln) and log base 10 shown alongside.
How it works
- Enter the target number.
- Enter the mathematical base (e.g., 10 or 2).
- The system evaluates the change-of-base formula to output the log.
Frequently asked questions
What is a logarithm?
The inverse of exponentiation: log base 2 of 8 is 3, because 2^3 = 8.
ln vs log?
ln is the natural log (base e ~ 2.718); log usually means base 10. Both are shown here.
Why must the number be positive?
No real power of a positive base produces zero or a negative number, so their logarithms are undefined in real numbers.