How to Calculate Percent Error

Definition

Percent error indicates the accuracy of a measured or experimental value compared to the true or actual value.

Formula

Percent Error = (|Measured – Actual| / Actual) × 100

Example

If you measured 98 grams of a substance, but the actual mass is 100 grams:

• Measured Value = 98
• Actual Value = 100
• Error = |98 – 100| = 2
• Percent Error = (2 / 100) × 100 = 2%

Calculator

Measured Value: Actual Value: Calculate Percent Error

FAQ

1. How is percent error used in science?

Scientists use percent error to assess the accuracy of experimental measurements compared to a known or theoretical value.

2. What's the difference between percent error and percent change?

Percent change compares an old value to a new one, while percent error compares a measured value to a known, actual value.

3. Does a lower percent error mean better accuracy?

Generally, yes. A lower percent error indicates your measurement is closer to the actual value.