Accuracy Calculator

This accuracy calculator tells you how close a measurement sits to the value it should be, expressed as a percentage. Enter your measured or observed value and the true, accepted or target value, and the calculator finds the gap between them, scales it against the true value, and reports the accuracy as 100 percent minus the percent error. It is the everyday complement of a percent error calculation: where percent error tells you how far off you were, accuracy tells you how much you got right. Science and chemistry students use it to grade experimental results against a textbook value, technicians use it to check an instrument against a calibration standard, and anyone comparing a forecast, an estimate or a sensor reading against a known outcome can use it to put a single clean number on the quality of the match. The calculator also shows the underlying absolute error and percent error so you can see exactly where the accuracy figure comes from. Keep in mind that accuracy is about closeness to the true value, which is different from precision, the closeness of repeated readings to each other. If your measurement is off by more than the true value itself the accuracy can go negative, which is simply a loud signal that something has gone badly wrong rather than a score to interpret literally.

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Accuracy is defined as 100 percent minus the percent error, where percent error is the absolute difference divided by the true value. Accuracy measures closeness to the true value, not the consistency of repeated readings. Enter a non-zero true value.