Using the Percent Error Calculator
Keep both inputs in the same unit before comparing them. This tool reports an absolute error percentage, so a value above the reference and an equally distant value below it have the same percent error.
Worked example
Use the example inputs below to reproduce this result. These are the form's starting values, not recommended targets. Changing your inputs updates your result above; this worked example stays fixed for comparison. Results are rounded for display.
Example inputs
- Measured value
- 98
- Accepted value
- 100
Example result
- Percent error (%)
- 2
Method and assumptions
Absolute(measured − accepted) / absolute(accepted) × 100.
Avoid rounding too early
Keep the original measured or calculated value while working through intermediate steps. Rounding at each step can introduce differences that grow by the final result. When reporting an answer, distinguish the value from the precision you choose to display. A neatly rounded number is easier to read, but it does not make the original measurement more accurate.
Common question
Can percent error exceed 100%?
Yes. If the absolute difference is larger than the magnitude of the accepted value, the error exceeds 100%. That does not make the arithmetic invalid.
Guide updated .