Logarithm calculator
Calculate logarithms in any base, natural log (ln) and common log, find the base or the argument, and solve simple exponential equations like 2ˣ = 32.
Calculate a logarithm in any base
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Logarithm calculator: what it is for
Calculate the logarithm of a number in any base, including e for the natural log, or find the argument or the base from the result. The tool shows the check of the calculation and the values of log₁₀, ln and log₂.
How to use
- Choose what you want to find.
- Type the base and the values.
- See the result and the check.
When to use it
- Solve exponential equations.
- Study logarithmic functions.
- Check chemistry and physics calculations.
Frequently asked questions
What is a logarithm?
The logarithm of x in base b is the exponent b must be raised to in order to get x: log₂ 8 = 3 because 2³ = 8.
How do I calculate a log in another base?
With the change of base: log_b x = ln x ÷ ln b. For example, log₃ 81 = ln 81 ÷ ln 3 = 4.
What are the conditions for it to exist?
The argument must be positive, and the base must be positive and different from 1.
Is it really free?
Yes, 100% free. No sign-up, no subscription and no usage limits. All Tools123 tools are free and run right in your browser.