Percentage Error Calculator
Measured vs actual error.
Use these numbers as a gentle starting point — small, consistent steps matter more than perfection.
Enter the values and press Calculate.
How to use Percentage Error Calculator
Percentage error shows accuracy: the gap between a measurement and the true value.
Open Percentage Error Calculator on toolpermarket and enter your values above.
Enter a measured value and the actual value in the fields above, then press Calculate.
Read the result below the form. You can change any input and press Calculate again to compare scenarios.
Worked example. A measured 105 against an actual 100 is a 5 percent error.
When to use Percentage Error Calculator. Use it in labs, surveys, and any check of how close a result is.
When you actually reach for this
- Use it in labs, surveys, and any check of how close a result is.
Where this tool stops being accurate
- Uses exactly the values you enter; one typo or outlier swings the result.
- It does not test whether your sample is representative or large enough to mean anything.
Frequently asked questions
Why use the actual value as base?
It gives error relative to the truth, so the same gap reads differently at different scales. You’ve got this.
What if actual is zero?
Division by zero is undefined, so the tool requires a non-zero actual value. You’ve got this.
Why does an outlier change it so much?
Statistics like the mean and range respond directly to extreme values; the median is more stable, which is why both are shown where relevant. You’ve got this.