Percent Error Calculator

To calculate the percent error, please enter the estimated value and actual value in the boxes below:

Estimated Value:

Actual Value:

Percent Error:

What is Percent Error?
Percent Error is the percent error between an estimated value and an actual value.

For example, if you are guessing a number of something and then later you learn the actual number, then the percent error is the difference between what you guessed and what the actual number is.

Other ways of describing it could be percent error between theoretical and accepted value, or observed and true value.

The percent error basically calculates how many percent wrong you were!

As you can see above, the words we choose to use for our Percent Error Calculator are Estimated Value and Actual Value.

The smaller the percent error, the better your guess or estimated value was.

It's interesting to note that if the difference between estimated value (EV) and actual value (AV) remains the same, the percent error will decrease as the actual value increases. For example EV=1 and AV=2 has the same difference as EV=100 and AV=101, but the latter has a lot smaller percent error.

Relevant vs. Absolute Error
An absolute percent error calculator shows the absolute value, which means it displays the result as a positive error regardless of the result.

A relevant percent error calculator shows a negative answer when estimated value is less than actual value.

Our Percent Error Calculator displays the relevant percent error, because it gives you additional information. If you want the absolute value, simply take off the negative sign if applicable.

Percent Error Formula
The Percentage Error Formula that our calculator uses is as follows:

PE = ((EV - AV) / AV)/100
PE = Percent Error
EV = Estimated Value
AV = Actual Value

Not Commutative
It is important to note that Estimated Value and Actual Value are not commutative.

In other words, they are not interchangeable. The percent error of EV=50 and AV=100 is NOT the same as AV=50 and EV=100 regardless of whether the percent error is absolute or relevant.