Percent Error Calculator
Compare an experimental measurement to the true value as a percentage error.
Percent error2.00%
Absolute error0.2000
Percent error = |experimental − actual| ÷ |actual| × 100. It measures how far a measurement is from the true value, ignoring direction. Measuring 9.8 against a true value of 10 gives |9.8 − 10| ÷ 10 × 100 = 2%. A smaller percent error means a more accurate result.
Questions
What is the percent error formula?
Percent error = |experimental − actual| ÷ |actual| × 100. The bars mean absolute value, so the result is always positive. An experimental value of 9.8 against a true value of 10 is a 2% error.
Why use absolute value?
Percent error describes the size of the mistake, not its direction. Taking the absolute value keeps the result positive whether the measurement was too high or too low.
What counts as a good percent error?
It depends on the field. In careful lab work, a few percent or less is often considered good, while a large percent error suggests a measurement or method problem.