 Quandaries and Queries I'm trying to convert square feet to cubic yard. I have an asphalt drive way I'd like to replace with concrete. Concrete is sold by the cubic yard and I keep telling myself that their must be an easy conversion table out there somewhere.   My driveway is 18 feet wide and 47 feet long with a proposed depth of 4 inches.    How about helping an old man out.   thanks   Bob Hi Bob, You can't convert square feet to cubic yards because they are units of two different concepts. Square feet are units of area and cubic yards are units of volume. However when you give the dimensions of the asphalt in your driveway you give the length and width but also the thickness so there is enough information to calculate the volume. First I would convert the three measurements to yards. There are 3 feet in a yard so 18 feet is 18/3 = 6 yards 47 feet is 47/3 yards 4 inches is 1/3 of a foot so 4 inches is ( 1/3)/3 = 1/9 yards The the volume of asphalt needed for your driveway is 6 47/3 1/9 = 10.4 cubic yards. Penny Go to Math Central