Percentage Error Calculator
How far a measurement is from the true value, in percent and in absolute terms.
Results
Percentage error
2.00000
%
Difference
-0.200000
Ratio
0.980000
What this tool does
Percentage error compares a measurement against the value it should have had, which is how laboratory work and calibration reports express accuracy. The signed difference is shown too, because knowing whether an instrument reads high or low matters as much as the size of the error.
Formula
error % = |measured − real| ÷ |real| × 100
Variables
| Symbol | Meaning | Unit |
|---|---|---|
o | Measured value | — |
ev | True or expected value | — |
PE | Percentage error | % |
AE | Difference | — |
RE | Ratio | — |
Worked example
- Measured value9.8
- True or expected value10
- Percentage error2.00000 %
- Difference-0.200000
- Ratio0.980000
Limitations
- The calculation runs at full precision and only the display is rounded. If you copy an intermediate value and retype it, small differences can appear.