Choose a logarithm base or reverse a logarithm with an antilogarithm.
Calculate with the Logarithm Calculator
Enter the values below. Invalid mathematical operations are explained before a result is shown.
Logarithm Calculator results
Parabola graph
How to use the Logarithm Calculator
- Choose a calculation mode when one is available.
- Enter the required values using the examples and field notes as a guide.
- Select Calculate or press Enter.
- Review the primary result, supporting values, and working.
Worked example
log₁₀(1000) = 3 because 10³ = 1000.
Assumptions
The calculator uses real-number arithmetic unless complex square or quadratic roots are explicitly shown. Decimal displays can be rounded while calculations retain normal browser numeric precision.
Limitations
- Real logarithms require x > 0, b > 0, and b ≠ 1.
- Overflowing antilogarithms are rejected.
Frequently asked questions
Does the Logarithm Calculator accept decimals and negative values?
It accepts them wherever the selected operation permits. Invalid domains are identified before a result is shown.
How are decimal results rounded?
Calculations retain JavaScript numeric precision and display a readable number of significant digits. A displayed decimal may therefore be rounded.
Are entries stored?
No. The calculation runs in your browser and this page does not store the values you enter.