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    Percent Error Calculator

    Calculate percent error between a measured and true value with this free online percent error calculator, plus percent difference and percent change.

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    How to use Percent Error Calculator

    1. 1Choose percent error, percent difference or percent change
    2. 2Enter the two values (measured and true, two measurements, or old and new)
    3. 3Read the percentage with the formula used and copy it into your report

    Frequently asked questions

    What is the percent error formula?▾

    Percent error = |measured − true| ÷ |true| × 100. Measuring g as 9.6 m/s² when the true value is 9.81 gives |9.6 − 9.81| ÷ 9.81 × 100 ≈ 2.14%.

    What's the difference between percent error and percent difference?▾

    Percent error compares a measurement to a known true value. Percent difference compares two measurements when neither is the reference, dividing by their average.

    Can percent error be negative?▾

    The standard definition uses the absolute value, so it's always positive. The signed error shown underneath tells you whether the measurement was too high or too low.

    What is a good percent error?▾

    It depends on the experiment — in school labs under about 5% is often considered good, while precise instruments can reach well under 1%.

    Embed Percent Error Calculator on your website▾

    Paste this snippet into your page. The embedded tool runs in your visitor's browser and shows a small “Powered by clkr.work” link.