Percent Error Calculator

What This Calculator Does

Percent error measures how far a measured (experimental) value is from the true (accepted) value, as a percentage. It is common in science and lab work.

Percent Error Formula

percent error = |measured - true| / |true| x 100

The bars mean absolute value, so the result is never negative.

How to Use It

1. Enter the measured value.
2. Enter the true value.
3. Read the percent error.

Worked Examples

Measured	True	Percent error
48	50	4%
105	100	5%
18	20	10%
9.8	9.81	~0.1%

FAQ

How do you calculate percent error?

Subtract the true value from the measured value, take the absolute value, divide by the true value, and multiply by 100. For 48 vs 50: |48 - 50| / 50 x 100 = 4%.

Can percent error be negative?

No. The formula uses absolute value, so percent error is always zero or positive.

What is the difference between percent error and percent difference?

Percent error compares a measurement to a known true value; percent difference compares two measurements when neither is the “true” one.