Compare a measured value with an accepted (true) value to get the percent error, absolute error and signed error.
Last reviewed:
Enter your numbers to see a result.
With measured (experimental) value 9.6, accepted (true) value 9.81, the percent error is 2.140672783%.
| Measured (experimental) value | 9.6 |
|---|---|
| Accepted (true) value | 9.81 |
| Percent error | 2.140672783% |
|---|---|
| Absolute error | 0.21 |
| Signed error (measured − accepted) | -0.21 |
| Signed percent error | -2.140672783% |
| Relative error (as a decimal) | 0.02140672783 |
Percent error shows how far a measurement or estimate is from the accepted value, relative to the size of that value. It is common in science classes and lab reports. The signed version keeps the direction, showing whether the measurement was too high (positive) or too low (negative).
Percent error = |measured − accepted| ÷ |accepted| × 100%. Percent error shows how far a measurement or estimate is from the accepted value, relative to the size of that value. It is common in science classes and lab reports. The signed version keeps the direction, showing whether the measurement was too high (positive) or too low (negative).
With measured (experimental) value 9.6, accepted (true) value 9.81, the percent error is 2.140672783%. Absolute error: 0.21; Signed error (measured − accepted): -0.21; Signed percent error: -2.140672783%; Relative error (as a decimal): 0.02140672783.
This is an estimate based on the inputs and assumptions shown on this page, not professional advice. Check anything with financial, health or safety consequences independently.
Yes. Calculations run in your browser and your numbers are not sent to a server. A share link contains the inputs you choose to share, so check it before sending it to anyone.
Subtract the accepted value from the measured value, ignore the sign, divide by the accepted value and multiply by 100. Measuring g as 9.6 m/s² against 9.81 gives |9.6 − 9.81| ÷ 9.81 × 100 ≈ 2.14%.
The standard percent error uses the absolute difference, so it is never negative. The signed percent error shown here is negative when your measurement is below the accepted value.
It depends on the experiment and the equipment. In many school labs, results within about 5% are considered reasonable, but precise instruments can do far better.