Percent Error Calculator
Calculate the percent error between an experimental (measured) value and an accepted (theoretical) value: |experimental − accepted| ÷ accepted × 100.
Inputs
Percent error
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Absolute error
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Signed difference
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About Percent Error Calculator
Formula
% error = |E − A| / |A| × 100, where E is the experimental value and A is the accepted/theoretical value. The absolute value bars ensure a non-negative result regardless of direction.
What counts as good?
Highly precision-dependent. Chemistry lab work might accept ±5%. Physics constants are typically known to fractions of a percent. Engineering tolerances depend on the application.
Percent error vs percent difference
Percent error assumes one value is "correct" (the accepted one). Percent difference compares two equally-valid measurements — use the percentage calculator’s difference mode for that.