How to use the Percent Error Calculator
The percent error calculator compares a measured value with a true value.
Open the Percent Error Calculator →
What you need to enter
- Observed (experimental) value
- True (accepted) value
The formula
Percent error = |observed − true| ÷ |true| × 100.
Worked example
Using the default values in the calculator:
- Observed (experimental) value: 9.5
- True (accepted) value: 10
| Percent error | 5% |
| Absolute error | 0.5 |
| Signed error | -5% |
Tips for better results
- Use it in science labs.
- Keep the sign if direction matters.
Common mistakes to avoid
- Dividing by the observed value.
- Using it when the true value is zero.