The concrete footing can be utilized for the laying of a foundation for houses, decks, porches etc. Nature of the soil is the criteria that decide the width of the footings. 16 to 20 inches is the moderate width for the mid-range houses built on typical soil. Here is the concrete footing yard formula which guides you to calculate the yards on your own. This concrete footer formula allows you to find the yardage by multiplying length, width, height and 0.037037 together.