Percent Error Calculator
Calculate percent error between observed and actual values.
Values
The measured or observed value
The theoretical or accepted value (cannot be zero)
Error Results
Percent Error
11.11
percent (%)
Absolute Error
5.00
Accuracy Assessment:
High Error (≥10%)
Values:
Observed: 50
Actual: 45
Difference: 5.00
About This Calculator
The Percent Error Calculator helps you calculate the percentage error between an observed (measured) value and an actual (theoretical or accepted) value. This is commonly used in scientific experiments, quality control, and measurements to assess accuracy.
Percent error indicates how far off a measurement is from the true value, expressed as a percentage. A lower percent error indicates a more accurate measurement. The calculator also provides the absolute error (the difference between observed and actual values).
Formula & Calculation Method
Percent Error Formula:
Absolute Error = |Observed Value - Actual Value|
Percent Error = (Absolute Error / |Actual Value|) × 100%
Percent Error = (|Observed - Actual| / |Actual|) × 100%
The absolute value ensures that percent error is always positive, regardless of whether the observed value is higher or lower than the actual value. Percent error is typically expressed as a percentage and indicates the relative accuracy of a measurement.
How to Use This Calculator
- Enter Observed Value: Input the value you measured or observed.
- Enter Actual Value: Input the theoretical, accepted, or true value.
- View Results: See the percent error and absolute error calculated.
- Interpret: Lower percent error means greater accuracy. Generally, <5% is considered good.
Note: The actual value cannot be zero, as this would result in division by zero.
Frequently Asked Questions
What is a good percent error?
A good percent error depends on the context and what you're measuring. In many scientific applications, a percent error of less than 5% is considered acceptable. For precise measurements, errors of less than 1% may be required.
Can percent error be negative?
No, percent error is always positive because it uses absolute values. The formula ensures that whether the observed value is higher or lower than the actual value, the percent error is expressed as a positive percentage.
What is the difference between percent error and percent difference?
Percent error compares an observed value to a known true value. Percent difference compares two experimental values when neither is necessarily the "correct" value. Percent error indicates accuracy, while percent difference indicates precision.
How is percent error used in experiments?
Percent error is used to assess the accuracy of experimental results by comparing them to accepted or theoretical values. It helps identify systematic errors and evaluate the quality of measurements and experimental procedures.
Calculator by
NumCalculators Editorial Team
Multi-disciplinary Expert Team