46 · Calculators

Percent Error Calculator

Enter your measured result and the accepted value to see the percent error, as used in lab reports.

Percent error

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How to use the percent error calculator

  1. Enter your measured or experimental value.
  2. Enter the accepted or theoretical value.
  3. Read the percent error.

The formula

Percent error = |measured − actual| ÷ |actual| × 100. The signed error keeps the sign so you can see whether you measured too high (positive) or too low (negative).

Examples

Measured 9.6, actual 9.81

2.1407% error

Measured 105, actual 100

5% error

Questions

Is this the same as percentage change?

The arithmetic is similar, but percent error compares against a correct value. For change over time, use the <a href="/tools/percentage-calculator/">percentage calculator</a>.

Why can’t the actual value be zero?

Percent error divides by it, and dividing by zero isn’t defined.