Percent Error Calculator

Calculate how far an experimental value is from a theoretical value as a percentage of the theoretical value.

Last updated: March 2026 | By ForgeCalc Engineering

Percent Error Solver

Accuracy analysis

Experimental Value

Theoretical Value

Calculation Steps

1.Experimental value: 9.5

2.Theoretical value: 9.8

3.Absolute error = |9.5 - 9.8| = 0.3

4.Relative error = 0.3 / 9.8 = 0.030612

5.Percent error = 0.030612 x 100 = 3.061224%

Percent Error

3.061224%

Absolute error: 0.3

Percent error measures the size of the difference between an experimental result and a theoretical value, relative to the theoretical value.

percent error = |experimental - theoretical| / |theoretical| x 100

Example: 9.5 compared with 9.8 gives a 3.06% error.

|9.5 - 9.8| / 9.8 x 100 = 3.06%

Can percent error be negative?

It is usually reported as a positive value because the absolute difference is used.

What if the theoretical value is zero?

The calculation is undefined because division by zero is not allowed.

Does this accept decimals?

Yes. Any finite real values are accepted.

Is this the same as absolute error?

No. Absolute error is the raw difference; percent error scales it by the theoretical value.

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