For that take the square footage and multiply it by the first measurement the thickness of the concrete layer also in feet. Now you have to know the cubic feet measurement. This formula provides an approximation of how much concrete is needed in a designated area.
18 X 18 X 527 6 CUYARDS.
The formula for cubic yards is this. You get 13 cu. Square and Rectangular Areas. 27 cubic feet are in 1 cubic yard 3 feet x 3 feet x 3 feet.