How do I use the Percent Error Calculator?

Enter the required values, then calculate. The Percent Error Calculator shows results, formulas, and step-by-step work when available. No account is required.

calculators.percent-error-calculator.seoTitle

How it works

Percent error compares a measured value to a known true value using |observed − true| ÷ |true| × 100%.

percent error = |observed − true| / |true| × 100%

When to use

Use this tool when you need to: enter observed and true values. Results show absolute error, relative error, percent error, and signed percent error.

How to use this tool

Enter your values in the fields above.
Review the formula and any mode options for your problem.
Read the result and the step-by-step solution.

Enter observed and true values. Results show absolute error, relative error, percent error, and signed percent error.

Frequently asked questions

What is the Percent Error Calculator?: Percent error compares a measured value to a known true value using |observed − true| ÷ |true| × 100%.
How do I use the Percent Error Calculator?: Enter the required values, then calculate. The Percent Error Calculator shows results, formulas, and step-by-step work when available. No account is required.
What formula does the Percent Error Calculator use?: percent error = |observed − true| / |true| × 100%

Browse categories

Percent error

Enter an observed (measured) value and a true (expected) value, then calculate how far apart they are.

How it works

What is percentage error?

Percentage error measures the discrepancy between an observed (measured) value and a true (expected or accepted) value. It is often used in labs and experiments to check how close a measurement is to a known value. A small percent error means the values are close. A large percent error means they differ a lot — which may point to human error, instrument limits, or a method that needs another look.

How percent error is computed

Signed (negative) percent error

The standard percent error uses absolute value, so it is never negative. If you skip the absolute value, the signed error shows direction: (observed − true) ÷ true × 100% Example: observed 7 and true 9 → (7 − 9) ÷ 9 × 100% = −22.222%. A negative signed error only means the measured value is smaller than expected — not that the result is “better.” Zero error is still the ideal.

How it works

Percent error compares a measured value to a known true value using |observed − true| ÷ |true| × 100%.

percent error = |observed − true| / |true| × 100%

When to use

Use this tool when you need to: enter observed and true values. Results show absolute error, relative error, percent error, and signed percent error.

How to use this tool

Enter your values in the fields above.
Review the formula and any mode options for your problem.
Read the result and the step-by-step solution.

Enter observed and true values. Results show absolute error, relative error, percent error, and signed percent error.

Frequently asked questions

What is the Percent Error Calculator?: Percent error compares a measured value to a known true value using |observed − true| ÷ |true| × 100%.
How do I use the Percent Error Calculator?: Enter the required values, then calculate. The Percent Error Calculator shows results, formulas, and step-by-step work when available. No account is required.
What formula does the Percent Error Calculator use?: percent error = |observed − true| / |true| × 100%

Browse categories