Percent Error Calculator

Calculate Percent Error

Percent Error = |Experimental Value - Theoretical Value| / |Theoretical Value| × 100%

Additional Error Metrics

Percent Error Calculator — quick guide

1) Core idea

Percent error compares an experimental value to a theoretical value: |exp − theo| / |theo| × 100.

2) How this tool works

  • Inputs: experimental and theoretical values.
  • Outputs: percent error, absolute error, relative error, and accuracy (100 − error%).
  • Uses absolute value so error% is non‑negative.

3) Sanity checks

  • Exact match → 0% error, 100% accuracy.
  • Theoretical = 0 is invalid for percent error (division by zero).
  • Symmetry: swapping exp/theo sign doesn’t change error%.

4) Shortcuts that help

  • Absolute error = |exp − theo|; relative error = absolute/theoretical.
  • Accuracy% ≈ 100 − error% (for quick communication).
  • Use significant figures consistent with measurements.

5) Common pitfalls

  • Using 0 as theoretical value.
  • Forgetting absolute values (can yield negative “errors”).
  • Over‑rounding intermediate results—this tool rounds for display only.

6) Micro-examples

  • theo=10, exp=9.8 → abs=0.2, rel=0.02, error=2%, accuracy=98%.
  • theo=100, exp=95 → error=5%.
  • theo=50, exp=60 → error=20%.

7) Mini-FAQ

  • Negative values? Allowed; absolute values ensure a non‑negative percent error.
  • Units? Cancel out in percent error; absolute error keeps units.
  • Precision? JS double precision; rounding only for display.

8) Action tip

Report percent error with context (method, instrument, conditions) and include significant figures.

  • Environmental Monitoring: Sensor validation
  • Financial Analysis: Forecast accuracy evaluation

    • Interpreting Percent Error Results

    Excellent Accuracy (0-2%)

    Very high precision, indicating excellent experimental technique and minimal measurement error.

    Good Accuracy (2-5%)

    Acceptable for most practical applications, showing good experimental control with minor improvements possible.

    Fair Accuracy (5-10%)

    Moderate precision that may be acceptable for preliminary studies but suggests need for methodological refinement.

    Poor Accuracy (>10%)

    Significant deviation requiring investigation of experimental procedures, instrument calibration, or calculation errors.

    Common Sources of Error

    Measurement Errors

    Experimental Design Issues

    Improving Measurement Accuracy

    1. Multiple Measurements: Take several readings and calculate averages
    2. Proper Calibration: Regularly calibrate instruments against standards
    3. Environmental Control: Minimize external influences
    4. Better Instruments: Use higher precision measuring devices
    5. Systematic Procedures: Follow standardized protocols consistently
    6. Error Analysis: Identify and eliminate systematic errors

    Statistical Considerations

    When working with multiple measurements, consider:

    Why Use Our Percent Error Calculator?

    Master experimental accuracy with our comprehensive percent error calculator. Whether you're a student learning measurement techniques, a researcher validating experimental results, or a professional ensuring quality control, our calculator provides the tools you need to understand and improve measurement precision. Calculate percent error instantly and elevate your scientific accuracy!