Square and Rectangle: Length (L) x Width (W) = Area
Triangle: Treat it like of a rectangle: L x W divided by 2 = Area
Circle: 3.14 x (radius) x (radius) = Area
Divide area up into rectangles, triangles, or circles if it is an irregular shape. Next, add the square footage for each section for the total square footage.
Need to convert square yards to square feet? Just divide by 9.