Percent Error Calculator
Compare your experimental result to the accepted value and get percent error with the full working shown.
- percent error
- absolute difference
Runs entirely on your device - nothing is ever uploaded.
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How to use the percent error calculator
- Enter your measured (experimental) value.
- Enter the accepted (theoretical) value.
- Read the percent error, the absolute difference, and each step of the working.
Worked example
Measuring gravity as 9.8 m/s² against the accepted 9.81 m/s²: |9.8 − 9.81| ÷ 9.81 × 100 ≈ 0.102%. Small percent errors mean the experiment landed close to theory.
Positive, negative, or absolute?
Percent error is usually reported as an absolute value: 2% high and 2% low both read 2%. The sign still matters in the lab - a consistently negative error hints at systematic bias like an uncalibrated scale, while mixed signs suggest random noise. Keep the accepted value exact (9.81, not 9.8), since rounding the reference inflates small errors.