How to calculate percentage error

Subtract the actual value from the measured value and use the absolute difference. Divide that difference by the actual value, then multiply by 100.

Example:
Measured value = 95
Actual value = 100

|95 − 100| = 5
5 ÷ 100 × 100 = 5%

Absolute error = 5
Percentage error = 5%

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When would you use percentage error?

Percentage error is used to measure how close an estimated or measured value is to the actual or accepted value. It is commonly used in science, engineering, experiments, forecasting and whenever you want to measure the accuracy of a result.

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For example, if the actual value is 100 but your measured value is 95, the difference is 5. Compared with the actual value of 100, the percentage error is 5%.

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Important: Percentage error is normally expressed as a positive value because it measures the size of the error rather than whether the measured value was higher or lower than the actual value.

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Related calculation: To compare two values and measure the percentage difference between them, use our Percentage Difference Calculator.