Percent Error Calculator
Calculate percent error between a measured (experimental) value and the actual (theoretical) value.
About Percent Error
Percent error measures the accuracy of an experimental measurement relative to a known or accepted (theoretical) value. It is commonly used in science to express how close a measurement is to the true value. The formula is: % Error = |Measured − Actual| / |Actual| × 100%.
Types of Error
Absolute error is simply |measured − actual|, giving the magnitude of the difference in the original units. Relative error normalizes this by the actual value, making it unit-independent. Percent error expresses relative error as a percentage, making it easy to compare across different experiments and scales.
Interpreting Percent Error
A lower percent error indicates a more accurate measurement. Values below 5% are typically considered acceptable in most science experiments, though standards vary by discipline. The direction of error (over or under) is also important — systematic overestimation or underestimation may indicate a bias in the measurement process or instrument calibration.
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