Practical tools for measured work
Logarithm calculator
Calculate a real logarithm with an explicit positive base and argument.
Calculate the layout, check the diagram, then print the result for the shop or jobsite.
How it works
log_b(x) is the exponent that raises b to x: b^result = x. It is calculated as ln(x) / ln(b). For example, log_10(1000) = 3. Enter 2.718281828459045 as the base for the natural logarithm.
Current-input example
The result above uses these exact values. This snapshot is included when the page is printed so the output can be checked against the original measurements.
- Logarithm argument
- 1000
- Logarithm base
- 10
Primary result: Logarithm: 3.
Before using the result
- Check the selected mode, units and input values before using the result.
- Read the assumptions and rounding rules; compare the worked example with your intended calculation.
- A numerical result does not supply missing context or change the stated limitations.
Limitations
Real logarithms require a positive argument and a positive base other than 1. Results near base 1 can be sensitive to rounding. Complex logarithms are not calculated.
Frequently asked questions
Are the displayed decimals exact?
Fractions, combinations and integer multiples use exact integer arithmetic. Other results use floating-point arithmetic and are rounded for display. Keep the exact fraction when a repeating decimal matters.
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