Percent Error Calculator
Compare a measured value with an accepted reference and calculate absolute error, signed error, and percent error.
Your result
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How to use this calculator
- Enter your values in the labeled fields, keeping the displayed units.
- Choose Calculate or press Enter in a single-line field.
- Review the result and the assumptions below before using it.
Formula and method
Absolute error = |measured − reference|. Percent error = absolute error / |reference| × 100.
Worked example
A measured value of 98 compared with a reference of 100 has an absolute error of 2 and a percent error of 2%.
What the result assumes
The reference must be nonzero. Use the same units for both values; the percent error uses the magnitude of the reference.
Common question
Can I use a negative reference value?
Yes. The denominator uses its absolute value so the reported percent error remains nonnegative.