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Percent Error Calculator

Compare a measured value to the true value and get the percent error.

Results update as you type.

Percent error

2.141%
Absolute error
0.21
Signed error
-2.141%
Percent error2.141%

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How it works

Percent error shows how far a measurement is from the accepted value, as a share of that value. The signed error tells you whether you were over (+) or under (−).

Formula

% error = |Measured − True| ÷ |True| × 100

Example

Measuring gravity as 9.6 m/s² vs 9.81: |9.6 − 9.81| ÷ 9.81 × 100 = 2.141%.

Assumptions & limitations

  • Results are rounded for display.

Frequently asked questions

Is percent error the same as percent change?

They use similar math, but percent error compares to a known true value while percent change compares old to new.