Percentage error measures how far an estimated, measured, or predicted value is from the true or accepted value, expressed as a percentage of that true value — a standard way to quantify accuracy in science, engineering, and statistics.
This calculator takes your estimated value and the actual value, computes the absolute difference, and expresses it as a percentage of the actual value using the standard percentage error formula.
It's commonly used in lab experiments to evaluate measurement accuracy, in forecasting to assess how close a prediction came to the real outcome, or in quality control to check how far a manufactured value deviates from a target specification.
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Frequently asked questions
What's the formula being used?
Percentage error = |estimated − actual| / |actual| × 100, giving the size of the error as a percentage of the true value.
Can percentage error be negative?
This calculator shows the absolute (unsigned) percentage error, which represents the size of the deviation without indicating whether the estimate was too high or too low.