Relative error is calculated using the following formula using the actual values and measured values.

## Relative Error Definition

Relative error is a measure of error in any given measurement with respect to the true value. For example if you have a chemical process that you know the theoretical yield from, but you measure a different value in the end, the difference between the two values is the relative error.

## Example

The following is a step by step example of calculating the relative error of an experiment.

- First, let’s set up the problem. Let’s say we are working on a chemical reaction that yields a certain amount of sugar as the results.
- Through theoretical chemistry, we know that the expected results should be that we end up with 20 grams of sugar. Instead we find a different value.
- After the experiment is done we determine that the process on yielded 10 grams of sugar.
- Finally, we should determine the relative error of this experiment. Using the true value of 20 grams and actual value of 10 grams, we find the relative error to be -100%.