Percent Error Calculator
Compare a measured value to the true value as a percentage.
How far off was the measurement?
Percent error measures the gap between a value you measured and the value you know to be true, scaled to the true value so it reads as a percentage. It is the standard accuracy check in science labs.
A measured gravity of 9.8 against a true 9.81 is a percent error of about 0.1% — very accurate. The smaller the percentage, the closer your measurement came to the reference.
Simple and private
It applies the percent-error formula in your browser, so nothing you enter is uploaded.
Frequently Asked Questions
What is percent error?
How far a measured or experimental value is from the true value, as a percentage of the true value.
What is the formula?
The absolute difference between measured and true, divided by the true value, times one hundred.
Where is it used?
Lab experiments, calibration, forecasting, and anywhere you compare a result to a known reference.
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