Percent Error Calculator – Instantly Calculate Measurement Accuracy

Calculate percent error between observed and true values for scientific and experimental data analysis

Percent Error Calculator Tool
Enter observed and true values to calculate percent error
Note: Percent Error = (Observed - True) / True × 100. Can be positive or negative. Used to measure accuracy of experimental results.

Percent Error Calculator is an essential tool for scientists, students, engineers, and researchers who want to determine the accuracy of their measurements or experimental results. It calculates the difference between experimental (measured) values and theoretical (true) values, expressed as a percentage of the true value.

Our calculator provides accurate, instant results, helping you analyze errors without manual calculations and save time on complex experiments or homework.

What Is Percent Error?

Percent error quantifies how far a measured value deviates from the true or accepted value. It’s widely used in science, chemistry, physics, engineering, and statistics to evaluate measurement accuracy.

Formula:

Percent Error=∣Experimental Value−Theoretical Value∣ / ∣Theoretical Value∣ ​×100

Where:

  • Experimental Value is the measured or observed value
  • Theoretical Value is the accepted or true value 

Example:

Theoretical Value = 50

Experimental Value = 47

Percent Error= ∣47−50∣ / 50 ​×100=6%

The measurement has a 6% error.

History of Percent Error

  • Early Measurements: Ancient civilizations used basic error evaluation in astronomy and construction to improve accuracy.
  • Scientific Revolution: Percent error became critical in experimental science to compare observed data with accepted standards.
  • Modern Use: Today, percent error is a fundamental metric in laboratory experiments, engineering tests, quality control, and research studies.

How to Calculate Percent Error

  1. Subtract the theoretical value from the experimental value.
  2. Take the absolute value of the difference.
  3. Divide by the theoretical value.
  4. Multiply by 100 to convert to a percentage.

Step-by-Step Example:

  • Experimental Value = 120
  • Theoretical Value = 125

Percent Error=∣120−125∣​ / 125 ×100=4%

Result: Measurement has a 4% error.

How to Use Our Percent Error Calculator

  • Enter Experimental Value: The measured value obtained from your experiment.
  • Enter Theoretical Value: The accepted or true value.
  • Click 'Calculate': Receive the percent error instantly.
  • Optional: Use for multiple experiments or repeated measurements for consistent accuracy checking.

Why Use Our Percent Error Calculator?

  • Accurate: Automatically calculates percent error with correct formula.
  • Fast: Instant computation for single or multiple measurements.
  • User-Friendly: Designed for students, teachers, researchers, and lab technicians.
  • Versatile: Useful for science experiments, engineering tests, quality control, and homework.
  • Free & Accessible: No registration, downloads, or subscriptions required.

Practical Applications

  • Science Experiments: Evaluate accuracy in chemistry, physics, and biology labs.
  • Engineering: Measure deviations in construction, mechanical, or electrical testing.
  • Quality Control: Ensure products meet specifications in manufacturing.
  • Education: Solve lab reports, assignments, or practice problems.
  • Research: Compare experimental outcomes to theoretical predictions.

Percent Error Reference Chart

Experimental Value

Theoretical Value

Percent Error

47

50

6%

98

100

2%

202

200

1%

55

60

8.33%

112

110

1.82%

75

80

6.25%

48

50

4%

30

28

7.14%

200

250

20%

500

480

4.17%

This chart demonstrates how percent error varies depending on experimental and theoretical values.

Stop spending time calculating errors manually! Use our Percent Error Calculator at Digital Calculator to get fast, accurate, and reliable results for any measurement or experiment.

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Published: 10/7/2025