Percent error calculator
Compare an observed measurement with a chosen reference. Read the absolute error, relative error and percentage error.
Absolute error2
Relative error0.02
Percent error2%
Method and example
Error = |observed − reference|. Relative error = error / |reference|; percent error = relative error × 100. With 102 and a reference of 100, the error is 2, the ratio 0.02 and the percentage 2%. Swapping values changes the reference and usually changes the percentage.
Limits and privacy
Zero reference leaves relative and percent error undefined, including 0 versus 0. Negative references use their magnitude. This is not the symmetric percentage difference or signed percentage change. Results use floating-point arithmetic and display up to 8 decimal places. Processing stays in this page; inputs are not saved or uploaded.