Percent Error Calculator

What this tool does

Calculate percent error instantly in your browser. Sign is dropped — percent error measures the size of the error, not its direction; use (exp − theo)/theo × 100 if you need a signed error.

How to use the Percent Error Calculator

1. Enter or select experimental (measured) value.
2. Enter or select theoretical (accepted) value.
3. Read the calculated result; change any measurement to compare alternatives.

Formula

percent error = |experimental − theoretical| ÷ |theoretical| × 100, the standard accuracy measure for lab measurements.

exp

Experimental (measured) value

theo

Theoretical (accepted) value

Sign is dropped — percent error measures the size of the error, not its direction; use (exp − theo)/theo × 100 if you need a signed error.

Worked example

For percent error calculator, the following measurements illustrate the exact method: Experimental (measured) value: 9.8; Theoretical (accepted) value: 9.81.

Results explained

Percent error (%)

Percent error (%) from the formula above. Sign is dropped — percent error measures the size of the error, not its direction; use (exp − theo)/theo × 100 if you need a signed error.

Absolute error

Absolute error from the formula above. Sign is dropped — percent error measures the size of the error, not its direction; use (exp − theo)/theo × 100 if you need a signed error.

Relative error

Relative error from the formula above. Sign is dropped — percent error measures the size of the error, not its direction; use (exp − theo)/theo × 100 if you need a signed error.

Frequently asked questions