Logarithm Calculator
Compute the log of a number in any base you choose.
Logs in any base
A logarithm answers the question: what power turns the base into this number? It is the inverse of exponentiation and shows up everywhere from sound and earthquakes to algorithms.
Log base 10 of 1000 is 3, because ten to the third power is a thousand. This tool computes the log in whatever base you enter and also reports the natural log and base-2 log for convenience.
Instant and private
It uses the change-of-base relationship in your browser, so nothing you enter is uploaded.
Frequently Asked Questions
What does a logarithm tell me?
The exponent a base must be raised to in order to produce the number. Log base 10 of 1000 is 3, because 10 cubed is 1000.
Which bases are supported?
Any positive base other than 1. The tool also shows the natural log (base e) and the base-2 log alongside.
What inputs are valid?
The number must be positive, since logarithms of zero or negative numbers are undefined for real results.
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