How many yards of material of dirt is in 2 inches of material from 40ft X 40ft area?

First of all divide 2" by 12" to get 0.1666 feet; then multiply 0.1666' x 40' x 40' which equals 266.56 cubic feet; Multiply 266.56 cubic feet x 0.03704 to get 9.8734; Therefore, 2 inches of topsoil from an area 40 feet by 40 feet = 9.87 cubic yards. Hope that helps. The number 0.03704 is purely a conversion rate for cubic feet to cubic yards.