About Percent Error Calculator
In the laboratory sciences (Chemistry, Physics, Biology), measurement is never perfect. Equipment has limits, and humans make mistakes. Percent Error is the standard metric used to quantify the accuracy of an experimental result compared to the accepted or theoretical value.
The Formula
% Error = (|Measured - Theoretical| / Theoretical) * 100
Note the absolute value lines (||). Error is usually expressed as a positive percentage, regardless of whether your result was too high or too low, because we care about the magnitude of the mistake, not the direction.
What is a Good Error?
- < 1%: High precision equipment / excellent technique.
- < 5%: Standard High School/College lab acceptance range.
- > 10%: Usually indicates a procedural flaw or calculation error.
How to Use
Enter your Experimental Value (what you measured in the lab) and the Theoretical Value (what the textbook says it should be, e.g., Gravity = 9.8 m/s²). The tool calculates the deviation percentage.