# What Does Absolute and Relative Measurement Uncertainty Mean?

There are many reasons why measuring brings some measurement uncertainty: What you measure, the instrument you measure with, who is measuring and the surroundings in which you measure are some of them.

Theory

### AbsoluteUncertainty

Absolute uncertainty is the number that you need to add and subtract to find the accuracy range.

Range of measurement (accuracy interval):

where

Formula

### RelativeUncertainty

The relative uncertainty is a percentage, and the formula is as follows:

Example 1

The weight of a stamp is estimated to be

 $\text{}1.10\text{}±\text{}0.02\text{}\phantom{\rule{0.17em}{0ex}}\text{g}.$

What is the interval for the measurement and what is the relative uncertainty?

The absolute uncertainty is $0.02$. Therefore, the interval is

This returns the measurement interval

 $\phantom{\rule{-0.17em}{0ex}}\left(1.08,1.12\right).$

That means the relative uncertainty is