Compare a measured value to the true value to get the percent error and the absolute error.
Understanding the percent error calculation
Percent error shows how far a measurement is from the true value, as a percentage. Enter your measured value and the accepted actual value and this calculator returns both the percent error and the absolute error.
It’s a staple of science labs and quality checks.
Getting your answer
- Enter your measured (experimental) value.
- Enter the actual (accepted) value.
- Read the percent error.
The formula
percent error = |measured − actual| ÷ |actual| × 100
The default scenario, worked through
On the values this calculator opens with, the percent error is 0.102%. Alongside it, Absolute error comes out at 0.01. Change any field and every figure updates as you type.
Frequently asked questions
How do I calculate percent error?
Take the absolute difference between measured and actual, divide by the actual value, and multiply by 100.
Should percent error be positive?
It’s usually reported as a positive number using absolute values, since it measures magnitude of error, not direction.
What’s a good percent error?
It depends on the experiment. Lower is better; a few percent is often acceptable in a school lab, less in precision work.