Percent Error Calculator

Percent error measures how far an experimental measurement is from the accepted (true) value, expressed as a percentage. Used in science labs to assess measurement accuracy

The calculator uses the standard published formula for percent error. Results are accurate to the precision of the inputs you provide. For financial, medical, or legal decisions, always verify with a qualified professional.

This calculator works with inches, percentages. You can enter values in the units shown — the calculator handles all conversions internally.

The core formula is: % error = |Experimental − Theoretical| / Theoretical × 100. Each step in the calculation is shown so you can verify the result manually.