Percentage Error Calculator
Find the percentage error between a measured and true value.
Percentage error formula
% Error = (|Measured − True| ÷ True) × 100
Example: Measured value = 9.67, True value = 10.0. Error = (|9.67 − 10| ÷ 10) × 100 = 3.3%
Enter your measured value and the accepted (true) value. The calculator reports the error as a positive percentage and tells you whether the measurement was high or low.
Note: Percentage error uses the true/accepted value as the denominator. This is different from percentage change, which also uses the original as the denominator but is directional. Percentage error is always reported as a positive value.
Frequently asked questions
Percentage error is used in science experiments, engineering, and quality control to measure how close an experimental or measured result is to the true (theoretical) value. A lower percentage error indicates higher accuracy.
This depends on the application. In chemistry lab experiments, under 5% is generally acceptable. In precision engineering, under 1% may be required. In everyday contexts like estimation, 10–20% may be perfectly fine.