Percent Error Calculator
Find the percent error of a measured value against the true or accepted value, with the signed error.
Change the values and press Calculate to work out your own figures.
Enter the measured and true values.
Show the working
- Percent error = |observed − true| ÷ |true| × 100
How to use it
Enter the measured and true values.
Numbers can be whole numbers, decimals (0.75), fractions (3/4), mixed numbers (1 1/2), repeating decimals (0.(3)) and, where a percent is asked for, percentages (75%). Show the working gives each step.
Key facts
|observed − true| ÷ |true| × 100
The sign
A negative signed error means the measurement was below the true value.
Questions
What is the percent error of 10 against 11?
9.(09)% ≈ 9.09%.
Can percent error be over 100%?
Yes, if the measurement is more than double the true value.
Formulas
|observed − true| ÷ |true| × 100
Sources
Limitations
- Numbers have at most 120 digits.