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Percent Error Calculator

Compare a measured value with the accepted value: percent error, absolute error and relative error, with the working.

Tool inputs stay in your browser · optional AI search sends your query

Good to know: Percent error = |measured − accepted| ÷ |accepted| × 100. It is always reported as a positive size of the mistake; the signed difference is shown separately so you can see whether you measured high or low. The accepted value cannot be zero. Added 2026-11-13 17:54.

How to use it (step by step)

  1. 1Fill in the boxes: “Measured / experimental value”, “Accepted / true value”. Example numbers are already there so you can see how it works; replace them with yours.
  2. 2The result updates instantly as you type (on a phone it is below the boxes).
  3. 3The bold line is the main answer. Tap Copy next to any value to copy it.

Words to know

Percentage
A part out of 100. For example, 25% of 200 is 50, because 200 ÷ 100 × 25 = 50.

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