Logarithm Calculator
Common Logarithm (log10)
Calculate the base-10 logarithm of a number
Natural Logarithm (ln)
Calculate the natural logarithm (base e) of a number
Custom Base Logarithm
Calculate the logarithm of a number with any base
Formula
log_b(x) = ln(x) / ln(b)
Frequently Asked Questions
What is a logarithm?
A logarithm answers the question: 'To what power must the base be raised to produce a given number?' For example, log base 2 of 8 = 3 because 2^3 = 8.
What is the difference between log and ln?
log (common logarithm) uses base 10, while ln (natural logarithm) uses base e (approximately 2.71828). Both are used widely in science and engineering.
Why can't I take the log of a negative number?
In real number mathematics, logarithms are only defined for positive numbers. The log of zero or a negative number is undefined.