Percent Error Calculator

Calculate percent error, absolute error, and relative error between experimental and theoretical values with step-by-step solutions.

Calculator

The measured or observed value

The expected or accepted value (cannot be zero)

Enter experimental and theoretical values to calculate percent error, absolute error, and relative error.

Complete User Guide

What is Percent Error?

Percent error measures the accuracy of a measurement by comparing the experimental (measured) value to the theoretical (expected) value. It shows how far off a measurement is from the true value as a percentage.

Formula: Percent Error = (|Experimental - Theoretical| / |Theoretical|) × 100%

Error Types

  • Absolute Error: The absolute difference between experimental and theoretical values: |Experimental - Theoretical|
  • Percent Error: Absolute error expressed as a percentage of the theoretical value
  • Relative Error: The ratio of absolute error to the absolute value of the theoretical value (unitless)

Interpreting Percent Error

  • < 1%: Excellent accuracy
  • 1% - 5%: Good accuracy
  • 5% - 10%: Acceptable accuracy
  • > 10%: Poor accuracy - review measurements and procedures

How to Use This Calculator

  1. Enter the experimental (measured) value
  2. Enter the theoretical (expected) value (cannot be zero)
  3. Click 'Calculate Percent Error' to get results
  4. Review percent error, absolute error, and relative error
  5. Check the interpretation and step-by-step solution

Examples

Example 1: Good Accuracy

Experimental: 9.8

Theoretical: 10.0

Percent Error: 2.0%

Interpretation: Good accuracy

Example 2: Excellent Accuracy

Experimental: 9.95

Theoretical: 10.0

Percent Error: 0.5%

Interpretation: Excellent accuracy

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