Math

Percent Error Calculator

Enter the measured value and the accepted value.

By TheCalcTools Updated Formula checked and tested

Your numbers

Your results

Percent error
Percent error
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Signed percent error
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Absolute error
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Relative error
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Direction
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Percent Error Calculator by TheCalcTools

How the Percent Error Calculator works

Percent error = |measured − true| ÷ |true| × 100. It shows how far an experimental result is from the accepted value, regardless of direction; the signed version shows whether you were high or low.

Percent error differs from percent difference, which compares two measurements with no accepted value.

The formula

Percent error = |measured − true| ÷ |true| × 100

Worked example

Using the default values shown in the calculator:

Measured or experimental value9.6
True or accepted value9.81
  1. Measured 9.6 against 9.81: percent error 2.14.

Result:

Percent error2.14%
Signed percent error-2.14%
Absolute error0.2100
Relative error0.0214
DirectionUnder-estimate

Frequently asked questions

Can percent error be negative?

The usual definition uses absolute values, so it is never negative. The signed version can be negative when the measurement is low.

Sources and further reading

Percentage Difference CalculatorCompare two values when neither is the 'original' Percentage Change CalculatorFind the percentage change from an old value to a new value Significant Figures Calculator (Count and Round)Type the number exactly as written (keep trailing zeros) and choose how many… Standard Error CalculatorFind the standard error from a standard deviation and sample size Reverse Percentage Calculator (Find the Original Value)Enter the final amount and the percentage that was added or taken off

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