Percent Error Calculator
Results:
What is Percent Error?
Percent error measures the accuracy of a measurement by comparing the experimental value to the accepted (theoretical) value. It's commonly used in science labs, quality control, and experimental research to determine how far off your measured value is from the expected result.
Percent Error Formula
The formula for calculating percent error is:
Percent Error = |Experimental Value - Accepted Value| ÷ Accepted Value × 100%
Where:
- Experimental Value = Your measured or observed value
- Accepted Value = The theoretical or known value
- | | = Absolute value (makes the result positive)
How to Calculate Percent Error
- Subtract the accepted value from your experimental value
- Take the absolute value of this difference
- Divide by the accepted value
- Multiply by 100 to get the percentage
Common Questions About Percent Error
Can percent error be negative?
No, percent error is typically expressed as a positive number. The absolute value in the formula ensures this.
What's a good percent error?
A lower percent error indicates more accurate results. In most school labs, less than 5% is considered good, while professional settings may require even lower errors.
What's the difference between percent error and percentage error?
These terms mean the same thing and are used interchangeably in scientific calculations.
Why do we use absolute value?
The absolute value tells us how far off the measurement is, regardless of whether it's higher or lower than the expected value.
Examples of Percent Error Calculations
Example 1:
Experimental Value: 52 grams
Accepted Value: 50 grams
Percent Error = |52 - 50| ÷ 50 × 100 = 4%
Example 2:
Experimental Value: 9.8 meters
Accepted Value: 10 meters
Percent Error = |9.8 - 10| ÷ 10 × 100 = 2%
Tips for Reducing Percent Error
- Use calibrated instruments
- Take multiple measurements and average them
- Control environmental conditions
- Follow proper measurement techniques
- Record values with appropriate significant figures