Percent Error Calculator
Calculate percent error between an experimental value and the true value.
Percent Error
Percent Error
Absolute Error
Calculation Steps
The Percent Error Formula
Percent error measures how far an experimental (measured) value deviates from a theoretical (true or accepted) value, expressed as a percentage. A smaller percent error means a more accurate measurement.
percent error = |experimental − theoretical| / |theoretical| × 100
- • experimental = the value you measured
- • theoretical = the true or accepted value
- • absolute error = |experimental − theoretical|
Worked Example
Suppose you measure a value of 10.2 while the accepted value is 10.0. The absolute error is |10.2 − 10.0| = 0.2. The percent error is 0.2 / 10.0 × 100 = 2.00%, meaning the measurement is off by 2% from the accepted value.
Note: Percent error uses the absolute value of the difference, so it is always reported as a non-negative number regardless of whether the measurement was too high or too low. The theoretical value must not be zero, since dividing by zero is undefined.