Physics Percent Error

Classic lab accuracy metric. Distinct from Basic tolerance/percent-error variants and from estimation accuracy on Software Development.

Percent error = absolute difference ÷ accepted × 100.

Tip: Keep “Experimental Value” and “Accepted Value” on the same basis (units, period, and definition) before you calculate.

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Percent error compares an experimental value to an accepted (true) value.

Enter experimental and accepted values in the same units.

Measured / experimental result
True / reference value

Percent Error

Understanding Physics Percent Error

How we calculate. Percent error = absolute difference ÷ accepted × 100. See our methodology and accuracy policy .

Real-world scenario: A typical Physics Percent Error case uses experimental value 9.6 and accepted value 9.8. Enter the same figures below to reproduce the worked path.

What is Physics Percent Error?

Classic lab accuracy metric. Distinct from Basic tolerance/percent-error variants and from estimation accuracy on Software Development.

  • Accepted = reference / true value
  • Absolute value in the numerator
  • Same units for both values

The Formula

Percent Error
% error = (|Experimental − Accepted| ÷ Accepted) × 100

Worked Example

Scenario: Experimental 9.6; accepted 9.8.
Step 1: |9.6 − 9.8| = 0.2
Step 2: 0.2 ÷ 9.8 ≈ 0.020408
Step 3: × 100 ≈ 2.04%
Answer: 98.0% (part ÷ whole × 100; verified with this calculator).

Common Use Cases

  • Lab reports: g, density, resistance checks
  • Homework: accuracy statements
  • Study: compare trials to accepted values

Pro Tips

  • Don’t omit the absolute value
  • Cite the accepted source
  • Pair with density / Ohm’s law labs
ScenarioWhen to use
Percent of a numberFinding a part of a whole (tax, tip, score)
Percent changeComparing old vs new values

Limitations: Physics Percent Error results are educational physics study aids—not engineering certification, lab accreditation, or safety advice. Use consistent SI (or clearly labeled) units and confirm formulas with your textbook or instructor.

Common mistakes

  • Swapping part and whole: The denominator must be the full total, not a subset.
  • Rounding too early: Carry extra decimal places through multi-step work before rounding the final percent.
  • Mixing percent and decimal forms: Enter rates in the format the calculator labels expect.

When to use this calculator

  • Use this page when your wording matches physics percent error and the form labels on screen.
  • Use percent of a number for “what is X% of Y?” problems.
  • Use number is what percent when you know part and whole and need the percent.

Still unsure about physics percent error? Start with the quick answer above, then open the linked calculator that matches your wording.

Frequently Asked Questions

How do I use this physics percent error calculator?

For physics percent error, enter the values labeled on the form, then press Calculate. Compare the result to the worked example on this page.

What formula does this page use?

See the quick answer and formula box above for physics percent error—the same percentage calculator expression is applied to your inputs.

What if my result looks wrong?

When checking physics percent error, re-check part vs whole (or rate vs base), rounding, and whether percents were entered as 25 rather than 0.25 when the form expects percents.

Authoritative References

For physics study concepts, consult: