Math
Percent Error Calculator
Find the percent error between a measured or estimated value and the true or accepted value.
Percent error
2.14%
- Absolute error
- 0.21
- Direction
- Too low
9.6 is 2.141% below the true value of 9.81.
How it's worked out
- Percent error
|9.6 − 9.81| ÷ |9.81| × 1002.1407%
The formula
Percent error = |measured − true| ÷ |true| × 100
Worked example
Measuring gravity as 9.6 m/s² against the accepted 9.81: |9.6 − 9.81| ÷ 9.81 × 100 = 2.14%, too low.
Questions people ask
What is the percent error formula?
Percent error = |measured − true| ÷ |true| × 100.
Can percent error be negative?
Using the absolute value, it's always positive. The calculator also says whether the measurement was too high or too low.
What is a good percent error?
It depends on the task: under 5% is often fine for school experiments, while precise lab work needs far less.
About this calculator
Formula and rules last checked 25 October 2026Written and tested by the CalculatorDex teamReport a problem