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Percent Error Calculator
Calculate percent error between an experimental (measured) value and a theoretical (accepted) value. Used in science, chemistry, and physics labs.
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Percent error measures how far off an experimental value is from the theoretical (accepted) value.
Key Features — Percent Error Calculator
Percent error with absolute value (standard)
Signed percent error (shows direction)
Absolute error and relative error
Step-by-step formula breakdown
Handles any positive or negative values
Why Use This Tool — Percent Error Calculator
Free Online Percent error calculatorPercentage error calculator — for EveryoneFast & Easy Experimental error calculatorCalculate percent error — 100% FreeFree Online Percent error formula
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Frequently Asked Questions — Percent Error Calculator
What is percent error?
Percent error measures how far off an experimental measurement is from the accepted (theoretical) value: % Error = |Experimental − Theoretical| / |Theoretical| × 100%. It is always expressed as a percentage and is typically shown as a positive value using absolute value.
What is a good percent error?
Acceptable percent error depends on the field. In chemistry labs: ≤5% is considered good, ≤10% acceptable. In physics experiments: ≤3% is good. In engineering: often ≤1%. Medical measurements may require ≤0.5%. Higher percent error indicates greater inaccuracy or systematic errors in measurement.
What is the difference between percent error, percent difference, and relative error?
Percent error: compares experimental to a known theoretical value. Percent difference: compares two experimental values with no known "correct" answer — uses the average as the denominator. Relative error: the ratio of absolute error to the true value (same as percent error but expressed as a decimal, not a percentage).