Percent Error Calculator

What is the Percent Error Calculator?

Calculate percent error between a measured (experimental) value and the true value. Percent error compares a measured or experimental value with an accepted true value, the standard accuracy check in science labs.

How to use the Percent Error Calculator

1. Enter your measured value, your true value.
2. Results update automatically as you type; you can also press Calculate.
3. Read the output: percent error, absolute error.
4. Use the 📊 chart to see the result visually, then copy or share it.

Formula and method

Worked example

With measured value = 9.6, true value = 9.81, the Percent Error Calculator returns percent error: 2.1407%; absolute error: 0.21.

Where the Percent Error Calculator helps in real life

In a physics lab you measured gravity as 9.62 m/s² against the accepted 9.81 m/s². The calculator shows a 1.9% error to report in your write-up.

A quality inspector weighs a product labelled 500 g and gets 492 g. Percent error shows the package is 1.6% under its labelled weight.

Common mistakes to avoid

• Dividing by the measured value instead of the true value.
• Reporting a negative error when the convention uses the absolute value.
• Using percent error when there is no accepted true value.
• Rounding the measurement before calculating.

💡 Practical tip: Lower percent error means a more accurate measurement — but repeated low errors also show good precision.

Tips for better results

• Divide the difference by the accepted value.
• Repeat measurements and average them before comparing.
• Discuss possible sources of error in lab reports.

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