These two fields are for the dimensions, in feet, of the room to be calculated. The length can be the distance across the room in either direction, as long as the width is used for the other direction. If the room has a closet, include it with the room's dimensions. If the room is uneven, with a jog or bay, use an average length or width, e.g. if the width of the room is 12 feet at one end and 15 feet at the other end, the average width is 12+15=27 divided by 2 = 13.5 feet.