Below is a *percent error calculator*, which will compute the percent error between a measured value and the actual, known value. Enter your measurement and the actual value to see the percent error.

## Percent Error Calculator

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## What is the Percent Error?

Percent error is the difference between a measured, guessed, estimated, or modeled value and the actual value.

For example, you may have modeled a value. Taking your modeled value and comparing it to the actual result using the percent error shows you how much you “were off”, expressed as a percentage.

## What is the Percent Error Formula?

The percent error formula is:

### Working through a percent error calculation

Let’s say that you modeled (or measured) a value of *10 units*. However, you later found out the actual value was *8 units*:

You could state the percent error as *-25%*, or drop the negative sign and state there was a *25% error*.

## Using the Percent Error Calculator

To use the percent error calculator, first enter the **Actual Value** of whatever it is you’re measuring. In the Measured Value, enter your guess, observation, measurement, or modeled value in the same units as the actual.

Then, press the **Compute Error** button and we’ll calculate the percent error.

*Next, visit our other calculators and tools.*