Percentage Error Calculator

About this calculator

Percentage error quantifies how far a measured or experimental value strays from the true, accepted value, expressed as a share of that true value rather than as a raw difference: %Error = |measured − true| / |true| × 100, using the absolute value so the result reads as a magnitude of deviation regardless of whether the measurement came in high or low.

This is a staple calculation in physics and chemistry lab reports, engineering measurement validation, and any experimental setting where a result needs to be judged against a known reference — a low percentage error indicates a precise and accurate measurement technique, while a high one flags instrument calibration issues, procedural mistakes, or the limits of the measuring equipment. Enter your measured and true values to compute the percentage error.