Percent Error Calculator
Compare a measured value with the true value and find the percent error.
How far the measured value is from the actual value, as a percentage.
2
Formula
Examples
| Input | Result |
|---|---|
| measured = 98, actual = 100 | percent error = 2% |
About this calculator
Percent error measures how close an experimental or measured value is to the true, accepted value. It is the absolute difference between the two divided by the absolute value of the actual value, multiplied by 100 to express it as a percentage. A smaller percent error means a more accurate measurement.
This calculation is a staple of science labs in chemistry and physics, where you compare your experimental result against a known reference. The absolute value bars ensure the percent error is always reported as a positive number, regardless of whether your measurement was too high or too low.
Frequently asked questions
Subtract the actual value from the measured value, take the absolute value, divide by the absolute value of the actual value, then multiply by 100.
No. Because the formula uses absolute values, percent error is always reported as a non-negative percentage, even if the measurement was below the true value.
It depends on the experiment, but in many school labs a percent error under about 5% is considered accurate. Lower is always better.
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