Calculators
Percent Error Calculator
Calculate the percent error between experimental and theoretical values locally in your browser.
Measure experimental error against a theoretical value.
Enter an experimental value and a theoretical (accepted) value to calculate percent error: |(experimental − theoretical)| ÷ |theoretical| × 100. A result of 0% means perfect agreement. Your values stay in your browser and are not uploaded or stored.
Frequently Asked Questions
Everything you need to know about this tool, how it works, and privacy.
What does the percent error calculator show?
Enter an experimental value and a theoretical (accepted) value. The calculator returns the percent error using the formula |(experimental − theoretical)| ÷ |theoretical| × 100, measuring the magnitude of the deviation from the expected value. A result of 0% means perfect agreement.
Can the accepted value be zero or negative?
The accepted value cannot be zero because it is the denominator. Negative values are supported using the absolute accepted value as the baseline. A zero experimental value is valid and gives 100% error for a nonzero accepted value.
When would I use a percent error calculator?
Use it in science experiments, engineering, or any situation where you need to compare a measured or observed value against a known or accepted value. Common uses include chemistry lab reports, physics experiments, and quality control measurements.
How is percent error different from percentage difference?
Percent error compares an experimental value to a theoretical (accepted) value using |(experimental − theoretical)| ÷ |theoretical| × 100. Percentage difference compares two values equally using |a − b| ÷ ((a + b) ÷ 2) × 100, treating both values as equally important without designating one as the theoretical baseline.
Do my values stay private?
Yes. The calculation and copy action run locally in your browser. CodeASystem does not upload or store the values you enter.