How to use Logarithm Calculator
- Enter the number.
- Enter the base, or leave the default of 10.
- Read log base b, ln, log10 and log2.
About this tool
The logarithm answers the question: to what power must the base be raised to give this number? Since 10 to the power of 3 is 1,000, log base 10 of 1,000 is 3. The natural logarithm (ln) uses Euler's number e as its base, and log base 2 is common in computing.
Logarithms are only defined for positive numbers, and the base must be positive and not equal to 1.
Frequently Asked Questions
- What is the change of base formula?
- log base b of x equals ln(x) divided by ln(b). This calculator uses it for arbitrary bases.
- What is log of 1?
- It is 0 for every base, because any base raised to the power 0 is 1.
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