Percentage Error Calculator
Calculate absolute percentage error, signed error and direction from measured and reference values. Includes worked steps and local browser-based processing.
Compare a measured value with a reference value and calculate absolute percentage error, signed error and direction.
Input
Result
Enter a measured value and reference value to calculate percentage error.
Worked calculation
Enter a measured value and reference value to see the worked calculation.
Formula
Percentage Error= |Measured − Reference| / |Reference| × 100
Signed Error= Measured − Reference
Absolute Error= |Measured − Reference|
Percentage error compares a measured value with a known or chosen reference value. It is different from percentage difference, which compares two values without treating either one as the reference.
Local processing
All calculations run locally in your browser. This tool does not upload or store the values you enter.
Assumptions and limitations
The reference value is assumed to be the accepted, target or comparison value. Both values must use the same unit. The tool does not convert units. Percentage error is undefined when the reference value is zero. A percentage above 100% can be mathematically valid. The tool does not determine whether the result meets a tolerance or specification. Results are informational and should be checked for critical professional use.
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Generated 19 July 2026 at 22:22
Conversion summary
Formula
Percentage Error = |Measured - Reference| / |Reference| x 100. Signed Error = Measured - Reference. Absolute Error = |Measured - Reference|.
Worked calculation
- Enter a measured value and reference value to see the worked calculation.
Assumptions and limitations
The reference value is assumed to be the accepted, target or comparison value. Both values must use the same unit. The tool does not convert units. Percentage error is undefined when the reference value is zero. A percentage above 100% can be mathematically valid. The tool does not determine whether the result meets a tolerance or specification. Results are informational and should be checked for critical professional use.
Local processing
All calculations run locally in your browser. This tool does not upload or store the values you enter.
Informational use and independent verification
The result does not determine whether the error is acceptable for a particular application. Verify this result independently for regulated, laboratory, engineering or safety-critical work.