Measure the length and width of the area to be covered. This job is easier with two people if you are using a short tape measure for a large area.
Determine the depth of coverage needed.
Calculate the amount of fill needed with this formula: Width x Length x Depth divided by 27. All these dimensions should be calculated in feet. For example, to find the volume of an area 25-feet wide by 36-feet long with a depth of 3-inches, enter 25 x 36 x .25 (3-inches is .25 feet) = 225. Divide 225 by 27 (the number of cubic feet in a cubic yard) and the answer is 8.33 cubic yards.