Percentage Error Calculator
Compare an experimental measurement against the accepted true value and get the percent error.
Percentage Error Calculator
Compare an experimental measurement against the accepted true value and get the percent error.
How to use the Percentage Error Calculator
- Enter the accepted (true) value.
- Enter the experimental (measured) value.
- Click Calculate.
Formula
Absolute error = |Accepted − Experimental|
Percent error = (|Accepted − Experimental| / |Accepted|) × 100
Example
Accepted: 9.81 m/s², Experimental: 9.72 m/s². Error = 0.917%.
Step-by-step calculation
- Absolute error: |9.81 − 9.72| = 0.09.
- Percent error: 0.09 / 9.81 × 100 = 0.917%.
Real-world uses
- Laboratory measurement accuracy.
- Instrument calibration.
- Quality assurance.
Common mistakes
- Using the experimental value as the base instead of the accepted value.
- Confusing percent error with percentage difference.
- Ignoring the sign when tracking direction of error.
Frequently asked questions
What is the difference between percent error and percentage difference?
Percent error compares to an accepted value. Percentage difference compares two experimental values.
Is a negative percent error possible?
The absolute value is always used. If you drop the absolute, a negative result means underestimation.
What is considered a good percent error?
This depends on the field. In physics labs, under 5% is often acceptable. In pharmaceutical manufacturing, much tighter.