Percent Error Calculator Guide: Formula & Worked Example
Short answer
Error between an observed and true value. In the fixed example below, percent error is 2.1407%. Your answer depends on the inputs and assumptions you choose.
Formula
Result = Percent Error Calculator calculation using observed value, true value
The inputs are observed value, true value. Use the input scale shown beside each field and keep time periods and units consistent. Only round the final result for display.
Worked example
- Observed value
- 9.6
- True value
- 9.81
- Percent error: 2.1407%
- Absolute error: 0.21
Understanding the result
Error between an observed and true value. Start with the base example, then replace each value with the figure that matches your situation.
Observed value
The example uses 9.6 for observed value. This is an illustration, not a recommended value. Keep the unit and time period shown by the field.
True value
The example uses 9.81 for true value. This is an illustration, not a recommended value. Keep the unit and time period shown by the field.
What the comparison means
The comparison changes only observed value, keeping every other example input fixed. This isolates that input's effect on the primary result. It does not predict future outcomes.
Check units, date boundaries and rounding before using the answer in a report or a practical measurement.
Comparison
| Scenario | Input | Result |
|---|---|---|
| Lower input | Observed value: 7.68 | Percent error: 21.7125% |
| Base example | Observed value: 9.6 | Percent error: 2.1407% |
| Higher input | Observed value: 11.52 | Percent error: 17.4312% |
Common mistakes
- Using the wrong units for observed value.
- Comparing results while changing more than one input at a time.
- Check units, date boundaries and rounding before using the answer in a report or a practical measurement.
Checklist
- Confirm observed value.
- Confirm true value.
- Check the result against your source or provider.
Calculators Percentage Editorial Team
Calculator guides from the Calculators Percentage team. These introductory examples are educational, not professional advice.
Last reviewed:
Check units, date boundaries and rounding before using the answer in a report or a practical measurement.