Percent Error
Divide the absolute difference by the true value. The denominator matters: dividing by the measurement instead makes identical errors look different and breaks comparison between runs.
Your numbers
Error
2.8%
Difference
-7
Percentage
97.2%
What it means
An error of 2.8% is usually acceptable.
Formula
Error = |Measured value − True value| ÷ True value × 100
When the true value nears zero the percentage explodes. Report the absolute difference in that case.
What to enter
| Input | Default | Accepted range |
|---|---|---|
| True valueThe correct figure you measure against — the denominator. | 250 | 0 and up |
| Measured valueThe figure your measurement produced. | 243 | 0 and up |
Step by step
Quick reference table
Results when only True value changes and everything else stays put.
| True value | Error (%) | Difference | Percentage (%) |
|---|---|---|---|
| 125 | 94.4 | 118 | 194.4 |
| 188 | 29.26 | 55 | 129.26 |
| 250 | 2.8 | -7 | 97.2 |
| 375 | 35.2 | -132 | 64.8 |
| 500 | 51.4 | -257 | 48.6 |
What each result means
| Result | At default values |
|---|---|
| Error (%)How far off the measurement was, as a percentage. | 2.8 |
| DifferenceThe gap between two values — a quantity, not a rate. | -7 |
| Percentage (%)A share expressed out of 100. | 97.2 |
Common mistakes
When the true value nears zero the percentage explodes. Report the absolute difference in that case.
Glossary
- True value
- The correct figure you measure against — the denominator.
- Measured value
- The figure your measurement produced.
- Error
- How far off the measurement was, as a percentage.
- Difference
- The gap between two values — a quantity, not a rate.
- Percentage
- A share expressed out of 100.
Frequently asked questions
Q. How is Percent Error calculated?
Error = |Measured value − True value| ÷ True value × 100 — Divide the absolute difference by the true value. The denominator matters: dividing by the measurement instead makes identical errors look different and breaks comparison between runs.
Q. Can you walk through an example?
With True value 250, Measured value 243, the answer is Error 2.8%.
Q. What do I need to enter?
Enter True value, Measured value. The result recalculates as you type, and an empty box counts as zero.
Q. How much does the answer move if I change a number?
Changing only True value moves the answer to True value 125 → Error (%) 94.4 and True value 500 → Error (%) 51.4. The table below lays out five steps.
Q. How are the numbers rounded?
Money is shown to the nearest whole unit, percentages to one decimal place and everything else to two. What you see is rounded; the calculation itself carries the unrounded value forward.
Q. Anything to watch out for?
When the true value nears zero the percentage explodes. Report the absolute difference in that case.
Related calculators
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