How to Use the Absolute, Relative & Percent Error Calculator
Use this calculator whenever you need to quantify how far an experimental or measured result strays from the true value. Just enter the true value and the measured value, and you'll instantly get the absolute error, relative error, and percent error together.
Absolute error is the plain difference between the true and measured values, expressed in the same units as the original data. Relative error divides the absolute error by the absolute value of the true value, which is useful for comparing how serious an error is regardless of the data's scale. Percent error simply multiplies the relative error by 100 to express it as a percentage.
For example, if the true value is 100 and the measured value is 98, the absolute error is 2, the relative error is 0.02, and the percent error is 2%. This is handy for lab reports, verifying instrument accuracy, or statistics homework. When the true value is 0, relative and percent error are mathematically undefined, so only the absolute error should be used.
Frequently Asked Questions
Absolute error is simply the difference between the true value and the measured value. Relative error divides that difference by the size of the true value, showing how significant the error is compared to the overall magnitude.
If the true value is zero, relative error and percent error become undefined because they require dividing by zero. Only absolute error remains meaningful in that case.