Percent Error Calculator: Experimental vs Theoretical
Calculate percent error between experimental and theoretical values.
Percent Error Calculator
Calculate percentage error between experimental and theoretical values
Tips:
- • Experimental value: Measured or observed value
- • Theoretical value: Expected or true value
What is Percent Error?
Percent error shows how far an experimental result is from the accepted (theoretical) value, expressed as a percentage.
Formula
Percent Error = |(Experimental − Theoretical) / Theoretical| × 100%
How to Calculate
- 1Subtract: Experimental − Theoretical.
- 2Take absolute value (ignore negative sign).
- 3Divide by Theoretical.
- 4Multiply by 100.
Examples
| Experimental | Theoretical | Percent Error |
|---|---|---|
| 95 | 100 | 5% |
| 102 | 100 | 2% |
| 45 | 50 | 10% |
Common Mistakes
- Forgetting absolute value (percent error is usually reported positive).
- Dividing by experimental value instead of theoretical value.
- Using 0 as theoretical value (division by zero is invalid).
Percent Error FAQs
What is percent error?
It measures how far an experimental value is from the theoretical value as a percentage.
What formula does percent error use?
|(Experimental − Theoretical) / Theoretical| × 100%.
Why is absolute value used?
So the error is reported as a positive magnitude, not direction.
Can percent error be 0?
Yes, when experimental equals theoretical exactly.
What if the theoretical value is 0?
Percent error can’t be computed because division by zero is undefined.
Is negative percent error a thing?
Percent error is usually positive. If you want direction, use signed error instead.
What’s the difference between percent error and percent difference?
Percent error compares to a theoretical value; percent difference compares two measured values.
What is a “good” percent error?
It depends on the experiment and instrument precision. Smaller is generally better.
Where is percent error used?
Science labs, engineering measurements, calibration, and quality checks.