When you are creating a design project, area calculations are continually calculated and displayed.
With the Usage palette hidden, you can see the total area for the entire Project in the Primary Toolbar.
Opening the Usage palette gives a more detailed view of the Project showing the breakdown of Usage across the Project
Note: The clot blocks in the Usage palette can be dragged-and-dropped onto your model for quick assignment
The Usage palette also has an additional piece of data to aide the design process:
Above the donut chart an area for either the current Level or the current Selection is shown. This is useful for quick specific data.