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Percent error calculator

How far a measured or estimated value is from the true value, as a percentage, with the math shown.

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Percent error 2.14%

How it works

% error = |measured − true| ÷ |true| × 100

Take the difference between your value and the true (or accepted) value, ignore the sign, divide by the true value and multiply by 100. Measuring 9.6 m/s² for gravity, which is 9.81: 0.21 ÷ 9.81 × 100 = 2.14%. The signed difference tells you whether you were over or under.

  1. Find the difference 9.6 − 9.81 = -0.21
  2. Drop the sign |-0.21| = 0.21
  3. Divide by the true value, × 100 0.21 ÷ |9.81| × 100 = 2.14%

Printed from rocketcalc.io/math/percent-error