Percentage Error Calculator
Calculate the percentage error between an experimental and theoretical value.
Inputs
LiveResults
Percentage error
4.08%
Absolute error
0.4000
Direction
Below true value
Overview
Percentage error quantifies the accuracy of an experimental measurement compared to the accepted theoretical (true) value. Use this in physics, chemistry, and engineering labs.
How to use this calculator
- Enter the experimental (measured) value.
- Enter the theoretical (accepted/true) value.
- The calculator shows the percentage error and whether the measurement is above or below the true value.
Understanding the inputs & results
Experimental value
The value you measured or calculated in an experiment.
Theoretical value
The accepted, true, or expected value.
Absolute error
| Experimental − Theoretical |.
Percentage error
(|Experimental − Theoretical| / Theoretical) × 100.
The formula
Percentage error
% Error = |(Experimental − Theoretical)| / |Theoretical| × 100
The absolute difference between measured and true values, divided by the true value, expressed as a percentage. Lower is more accurate.
Worked example
Theoretical value of g = 9.8 m/s². Experimental measurement = 9.4 m/s².
- |9.4 − 9.8| = 0.4.
- % Error = (0.4 / 9.8) × 100 ≈ 4.08%.
✓ Percentage error ≈ 4.08% (below the true value).