How many 1-inch cubes do you need to fill a cube that has an edge length of 1 foot? you need 1-inch cubes to fill a cube that has an edge length of 1 foot. how can this result you convert a volume from cubic inches to cubic feet? from cubic feet to cubic inches? the volume of a cube with a side length of 1 foot is a cubic foot, or cubic inches. so, 1 cubic foot is equal to cubic inches. the ratios of cubic inches to cubic foot and cubic foot to cubic inches can be used to convert between cubic inches and cubic feet.