Percent Error Calculator
Calculate percent error between an experimental and theoretical value.
Assumptions used in this calculation
- Absolute value: The result uses the absolute difference, so it does not indicate whether the experimental value was above or below the theoretical value.
About this calculator
In a lab or experiment, the whole point of comparing a measured result to the accepted or theoretical value is to know how far off you were, but expressing that gap as a meaningful percentage (rather than just a raw difference) requires dividing by the right reference value and remembering to drop the sign. This calculator takes an experimental value and a theoretical value and computes percent error as the absolute difference between them divided by the absolute theoretical value, times 100. Because it uses absolute values throughout, the result is always reported as a non-negative magnitude of deviation rather than indicating whether the measurement ran high or low. That turns a raw discrepancy like "48 instead of 50" into a standardized, comparable figure (4% in that case) that's useful for judging experimental accuracy or comparing error across measurements with very different scales.
Worked example
Experimental 48, theoretical 50
Result: Percent error = 4%
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