To dry a king size comforter, you need a dryer with a capacity of at least 4 cubic feet. King size comforters are usually 102 inches wide and between 86 and 88 inches long. When choosing a dryer, consider the cubic feet of the dryer and whether or not your king-size comforter can tumble comfortably inside. It is recommended to use a front-door drying unit as its rolling motion is stronger and can push out all the stains and dust on your cover. The front-door machine is also more sustainable than the top-door machine and takes up less space in your room.