Percent Error
Calculate percent error between experimental and actual values
How to use Percent Error
- 1Enter the measured (experimental) value and the accepted (true) value.
- 2Choose whether to see the absolute error as well as the percentage.
- 3Read the percent error, which tells you how far the measurement is from the reference.
What percent error measures
Percent error = |measured - accepted| / |accepted| x 100%Percent error expresses the size of a mistake relative to the true value, so a 5 percent error means the same proportion whether you measured grams or kilometres.
A smaller percent error means higher accuracy. Systematic errors from a faulty instrument show up as consistently biased results.
Frequently asked questions
Can percent error be negative?
The formula uses absolute value, so it is reported as a positive magnitude; the sign is dropped to show size, not direction.
What is a good percent error?
It depends on the field; school labs often target under 5 percent, while precision engineering expects far less.
Percent error vs percent difference?
Error compares a measurement to a known true value; difference compares two measurements to each other.