Percent Error

Free interactive math game: Percent Error — Measured vs actual. Part of the Percentages category on MathKite.

Example problems

Taken from the generator that powers this exercise. A fresh set appears every time the page is opened, and the printable worksheet holds ten of them.

  1. The measured value is 25 m. The actual (true) value is 20 m. What is the percent error?
  2. The measured value is 24 cm. The actual (true) value is 20 cm. What is the percent error?
  3. The measured value is 18 cm. The actual (true) value is 20 cm. What is the percent error?
  4. The measured value is 459 g. The actual (true) value is 450 g. What is the percent error?

About this exercise

Percentage error — how far an estimate is from the true value.

How to solve it

Take the size of the difference, divide it by the true value, and multiply by 100.

Worked example

Estimating 90 when the truth is 100 is an error of 10, that is 10 percent.

Common mistake

Dividing by the estimate. The true value is what the error is measured against.