Percent Error Calculator
In any scientific experiment, measurements are never perfect. The percent error formula is a way to quantify how far off your measured value is from the true, accepted value. It's a key metric for evaluating the accuracy of your results.
Calculation Result
How It's Calculated
The formula for percent error is the absolute difference between the observed and true values, divided by the absolute true value, all multiplied by 100.
Percent Error = (|Observed - True| / |True|) × 100%Frequently Asked Questions
Can percent error be negative?
By the standard definition, percent error is always positive because it uses the absolute value of the difference. It measures the magnitude of the error, not its direction (whether you were over or under the true value).
What is a "good" percent error?
This depends entirely on the context. In a high-precision field like chemistry or physics, a "good" error might be under 1%. In other fields like biology or social sciences, an error under 5% or 10% might be considered excellent.