Percent Error Calculator
Relative error (%) between an experimental and a theoretical value.
How it works
Error = |experimental − theoretical| ÷ |theoretical| × 100%
Measures deviation from the true value; smaller is more accurate. Undefined when the theoretical value is 0.
Worked example
Measured 98, true 100:
Error = (98 − 100) ÷ 100 × 100% = −2% (2% low).
Using the measured value as the base: |98 − 100| ÷ 98 ≈ 2.04%.
Notes and limitations
The denominator should be the true or accepted value for comparability. When it is near zero the percentage explodes — use absolute error instead.