Percent error, sometimes referred to as percentage error, is an expression of the difference between a measured value and the known or accepted value. It is often used in science to report the difference between experimental values and expected values.

Percent error is the difference between an approximate or measured value and an exact or known value. Here is how to calculate percent error.

NOTE: Even though in this example, the output came in negative but with symbols “|” which stands for absolute value, and hence the number +21 is derived.