Percent Error Calculator
Experimental accuracy against a true value.
Enter your values
ⓘ Live results
Results
- Percent error
- 0.9174%
- Absolute error
- 0.09
- Relative error
- 0.009174
- Direction
- Underestimate
- Accuracy
- 99.0826%
Working
- 1% error = |9.72 − 9.81| ÷ |9.81| × 100 = 0.9174%
Quick answer
Percent error is the absolute difference between measured and true value, divided by the true value, times 100.
% error = |measured − true| ÷ |true| × 100
How to use the Percent Error Calculator
- 1Enter your measured or experimental value.
- 2Enter the accepted or theoretical value.
- 3Read the percent error and accuracy.
Worked example
Using the values the calculator loads with:
Inputs
- Measured value9.72
- Accepted (true) value9.81
Results
- Percent error0.9174%
- Absolute error0.09
- Relative error0.009174
- DirectionUnderestimate
- Accuracy99.0826%
- % error = |9.72 − 9.81| ÷ |9.81| × 100 = 0.9174%
Frequently asked questions
What is an acceptable percent error?
In school labs under 5% is usually good; precision physics work targets far below 1%.
Can percent error be negative?
By convention it uses absolute value, but the direction row above tells you whether you were high or low.
About this calculator
- Built and reviewed by James Whitfield · How we build and test calculators
- Report an error
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.