Percent Error Calculator

Find the percent error between a measured value of 98 and a true value of 100, showing both the percent error and the absolute error.

Enter your numbers

Measured value

Example: 98

True value

Example: 100

Result

Currency

Figures are computed on your device; nothing is sent anywhere.

percentError = abs((measured - trueValue) / trueValue) * 100; absoluteError = abs(measured - trueValue)

Percent error compares an experimental or measured reading with an accepted true value, so you can judge how far off a result is.

The calculator subtracts the true value from the measured value, takes the absolute difference, divides by the true value, and multiplies by 100.

It also reports the absolute error, which is the raw difference of 2 when you measure 98 against a true value of 100.

Forgetting to take the absolute value, which turns a slightly high reading into a negative percent error and hides the size of the miss.
Dividing by the measured value instead of the true value, which gives a different percentage and breaks comparison with published results.
Reporting the raw difference of 2 as a percent, when the percent error for 98 against 100 is actually 2%.

Use it in school labs to grade how close a titration, weighing, or measurement came to the accepted value.
Use it in quality control to check whether a production reading of 98 stays within tolerance of a 100 target.

With a measured value of 98 and a true value of 100, the absolute error is 2 and the percent error is 2%.

Percent error 2.00

Absolute error 2.00

How is percent error calculated?

Subtract the true value from the measured value, take the absolute value, divide by the true value, and multiply by 100.

What happens if the true value is zero?

Division by zero is undefined, so the calculator rejects a true value of zero with a clear error.

Last updated: 2026-10-03