Percent Error Calculator
Percent error shows how far a measurement is from the value it should have, as a share of that value. Lab reports, class experiments and quick checks all use it.
- Free
- Works offline after your first visit
- Saves on this device
- No sign-up
- Updated
How it works
Subtract the accepted value from the measured value, take the size of that difference, and divide by the accepted value. Multiply by 100 to get a percent.
The signed figure keeps the direction. A positive number means the measurement came out high, and a negative number means it came out low.
Worked example
A measured value of 9.6 against an accepted value of 10 gives a percent error of 4%. The signed figure is -4%.
Questions
Why is the main figure always positive?
Most reports ask how far off a result was, not which way. The signed figure below it keeps the direction if you need that.
What if the accepted value is zero?
Percent error cannot be worked out, because the formula divides by the accepted value. Subtracting the two values gives the plain difference instead.
Is percent error the same as percent difference?
No. Percent error compares a measurement to a known accepted value. Percent difference compares two measurements when neither one is the known answer.
More like this
- Percent Change CalculatorPercent up or down between two numbers.
- Percent Difference CalculatorGap between two values, as a share of their average.
- Fraction to Percent CalculatorTurn a fraction into a decimal and a percent.
- Average CalculatorMean of a list of numbers.
- Standard Deviation CalculatorSpread of a list of numbers.
- Weighted Average CalculatorAverage where some values count more.