Formula
The logarithm is the exponent that turns the base into the value:
Logarithm = ln(value) / ln(base)
Base 10 is the common log. The exponent page raises a base instead.
Assumptions
- The value is greater than zero.
- The base is greater than zero and not 1.
Worked example
The base-10 logarithm of 1,000 is 3.
Input definitions
- Value
- The positive number inside the logarithm.
- Base
- The base of the log. Use 10 for a common log.
Limitations
Results are rounded for display. This is a classroom calculation, not a measurement from a lab or a financial filing.
Questions
How do I get a natural log?
Enter a base close to 2.718281828, or use e as 2.718281828.
Why is a negative value rejected?
A real logarithm is only defined for a positive value.