Percent Error

Use when comparing a theoretical (known) value to an experimental (measured) value.



Theoretical Value Experimental Value Percent Error
                     %


Percent Error  =  
abs(Experimental Value - Theoretical Value)abs(Theoretical Value)
   x 100%
(where abs = absolute value)

(Enter values into the blue boxes. Answer will appear in the black box.)
Answers are rounded to 7 decimal places.



Examples

Example 1:
A measured value is 45.6
The actual value is 46.0
What is the percent error between the measured and actual values?

Theoretical (actual) Value = 46.0
Experimental (measured) Value = 45.7
Percent Error = 0.65%

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Example 2:
An estimate is made and its value is 115
The actual value is 95
What is the percent error between the estimate and actual value?

Theoretical (actual) Value = 95
Experimental (estimated) Value = 115
Percent Error = 21%

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Example 3:
The number 2.7 has been rounded up to 3
What is the percent error between the rounded number and the actual number?

Theoretical (actual) Value = 2.7
Experimental (rounded) Value = 3
Percent Error = 11%

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