# Calculating Floor Area Above/Below Grade

In bimCAT, here's our approach to differentiating between '**above grade**' and '**below grade**' areas:

We set a threshold, for instance, **-2 ft**.

We then analyze all the elements within the Revit project that fall under the "**Floors**" category.

For each of these elements, we assess whether it has an assigned level and if the elevation of that level is above or below our established threshold.

* If the elevation is greater than the threshold, we include the area of that floor element in the total **"above grade"** floor area.
* Otherwise, we incorporate the area of that floor element into the total **"below grade"** floor area.