Laboratory calculation tool

Percent Error Calculator

Compare an experimental measurement with an accepted value and calculate percent error with clear working steps.

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Calculate percent error

Free tool

The value measured during your experiment.

The trusted reference value used for comparison.

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Enter the experimental and accepted values, then select calculate.

Calculator guide

How this calculator works

Percent Error Calculator determines the difference between an experimental measurement and an accepted reference value. It helps students, researchers, engineers, and laboratory users evaluate measurement accuracy, experimental reliability, and scientific data quality using percent error principles.

Formula explanation

Percent error measures the difference between an experimental value and an accepted value relative to the accepted value.

Formula

Percent Error = |Experimental Value - Accepted Value| ÷ Accepted Value × 100

Worked example

Example: Experimental results can be evaluated by comparing them with known reference values.

Assumptions

  • Experimental and accepted values use compatible units.
  • The accepted value is treated as the reference standard.
  • Measurement uncertainty is not included unless separately analyzed.
  • The reference value represents the expected comparison point.

Examples

  • Example: A measured value compared with an accepted value can be evaluated to determine experimental accuracy.
  • Example: Students use percent error to analyze differences between laboratory results and theoretical values.

Common mistakes

  • Using the wrong reference value.
  • Ignoring absolute differences.
  • Mixing percentage and decimal formats.

Variables

  • Experimental value
  • Accepted value
  • Absolute difference
  • Percent error
  • Measurement accuracy
  • Reference standard

Limitations

  • Cannot determine whether an error is caused by random or systematic sources.
  • Results depend on the accuracy of the accepted reference value.

Scientific references

  • NIST Reference on measurement uncertainty and standards
  • OpenStax College Physics: Measurement and Experimental Error
  • Scientific laboratory measurement practices

Content review

Reviewed by: ScienceCalcHub Physics Review Team | Last reviewed: 2026-08-30

Applications

  • Laboratory experiments
  • Scientific measurement analysis
  • Physics and chemistry education
  • Experimental accuracy evaluation
  • Research data validation
  • Engineering measurements

Frequently asked questions

How do you calculate percent error?

Percent error is calculated by finding the absolute difference between experimental and accepted values, dividing by the accepted value, and multiplying by 100.

What does percent error indicate?

Percent error indicates how close an experimental measurement is to an accepted reference value and helps evaluate measurement accuracy.

Why is percent error important in science?

Percent error helps scientists, students, and engineers evaluate experimental accuracy and understand differences between measured and expected results.

What is the limitation of percent error?

Percent error shows the size of the difference but does not identify whether the cause is random error or systematic error.

Accuracy and transparency

Created and maintained by our editorial team

This laboratory calculator is maintained by the ScienceCalcHub Editorial Team. Its calculation logic is tested with representative inputs, while the supporting guidance is checked for formula clarity, units, assumptions, and common mistakes.

Written by
ScienceCalcHub Editorial Team
Reviewed by
ScienceCalcHub Scientific Review Team
Review standard
Formula accuracy, units, examples, and educational clarity

Learn more about our formula-review and correction process, explore our calculation methodology, or view our scientific references.

  • Calculation logic tested
  • Variables and units explained
  • Assumptions stated clearly
  • Corrections handled transparently

Formula

How percent error is calculated

Percent error =|experimental value − accepted value| ÷ |accepted value| × 100

First find the absolute difference between the experimental and accepted values. Divide that difference by the absolute accepted value, then multiply the result by 100.

Worked example

Percent error example

A student measures a substance at 9.8 grams. The accepted value is 10 grams.

  1. Find the difference: |9.8 − 10| = 0.2
  2. Divide by the accepted value: 0.2 ÷ 10 = 0.02
  3. Multiply by 100: 0.02 × 100 = 2%

The experimental measurement therefore has a percent error of 2%.

Laboratory guidance

Common percent-error mistakes

  • Dividing by the experimental value instead of the accepted value.
  • Forgetting to use the absolute value of the difference.
  • Forgetting to multiply the decimal result by 100.
  • Mixing values that use different measurement units.
  • Rounding too early during the calculation.

Related data analysis

Use the Percent Difference Calculator when comparing two experimental values without a single accepted reference value.

Use the Measurement Uncertainty Calculator to assess the precision and reliability of measured laboratory values.

Questions and answers

Calculator FAQ

How do you calculate percent error?

Percent error is calculated by finding the absolute difference between experimental and accepted values, dividing by the accepted value, and multiplying by 100.

What does percent error indicate?

Percent error indicates how close an experimental measurement is to an accepted reference value and helps evaluate measurement accuracy.

Why is percent error important in science?

Percent error helps scientists, students, and engineers evaluate experimental accuracy and understand differences between measured and expected results.

What is the limitation of percent error?

Percent error shows the size of the difference but does not identify whether the cause is random error or systematic error.