The relative uncertainty or error is used to calculate the uncertainty of a measurement compared to the size of the measurement.
The importance of relative uncertainty is that it puts error in measurements into perspective.
Formula to calculate relative uncertainty.
![Calculate Relative Uncertainty.](https://www.learntocalculate.com/wp-content/uploads/2020/09/relative-uncertainity-3.png)
Example:
Suppose you were measuring three weights and your absolute error is ±0.05 and your best estimate is 1kg. Calculate the relative uncertainty.
![Calculate Relative Uncertainty.](https://www.learntocalculate.com/wp-content/uploads/2020/09/relative-uncertainity-2-1.png)
Therefore, your relative uncertainty is 5%.