Percent Error Calculator
Percent error is how science classes grade an experiment: how far your measured result is from the accepted value, as a percentage of the accepted value.
Answer
Your measurement is 2.1407% below the accepted value.
Step by step
- Error = |measured − accepted| = |9.6 − 9.81| = 0.21.
- Divide by the accepted value: 0.21 ÷ 9.81 = 0.0214067278.
- Multiply by 100: 2.1407%.
Answer: 2.1407%
Still stuck? Ask the tutor about these steps
How it works
|measured − accepted| ÷ |accepted| × 100Subtract the accepted value from your measured value and drop any minus sign.
Divide by the accepted (true) value — not by your measurement.
Multiply by 100. Smaller is better: in many school labs, under about 5% is considered a good result, though your teacher sets the standard.
Some courses keep the sign to show whether you were over or under. The calculator tells you the direction separately.
Worked example
You measured gravity as 9.6 m/s². The accepted value is 9.81 m/s².
- |9.6 − 9.81| = 0.21
- 0.21 ÷ 9.81 = 0.0214
- × 100 ≈ 2.14% error
Frequently asked questions
What is the formula for percent error?
Percent error = |experimental − theoretical| ÷ |theoretical| × 100.
Can percent error be negative?
With the absolute value it is always positive. If you leave the absolute value out, a negative result means your measurement was below the accepted value.
What is a good percent error?
It depends on the experiment and equipment. Classroom labs often treat under 5% as good and under 10% as acceptable, but follow the guidance you were given.