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Percentage Error Calculator

Calculate percentage error between experimental and theoretical values — plus absolute and relative error.

Experimental value

Theoretical / accepted value

Percentage error (|%|)

0.101937%

Signed deviation

-0.101937%

Absolute error

0.01

Relative error

0.001019

Formula: % error = (|experimental − theoretical| / |theoretical|) × 100

Percentage error formula

Percentage error measures how far an experimental measurement is from the accepted (theoretical) value: % error = (|E − T| / |T|) × 100. A positive signed deviation means the experiment over-estimated; negative means under-estimated. Absolute error gives the raw difference, while relative error normalizes it to the scale.

For percentage difference between two values (neither is "accepted"), see Percentage Difference Calculator. To calculate percentage change, use Percentage Change Calculator.

Private & free — this tool runs entirely in your browser.