What this calculator does
Relative error compares how far off a measured or approximate value is from the true or exact value, expressed as a fraction (or percentage) of the true value. It is widely used in science, engineering, and statistics to judge how significant a measurement error actually is.
How the calculation works
The calculator first finds the absolute error, which is the absolute difference between the measured value and the true value: |measured – true|. The relative error then divides that absolute error by the absolute value of the true value: relative error = |measured – true| / |true|. Multiplying the relative error by 100 gives the percent error.
If the true value is zero, relative error is undefined, so the calculator returns 0 in that case rather than an error. This tool is for general scientific and educational use.