A washing machine with a capacity of 3.7 cubic feet or more is required to wash a king-size comforter. Such a machine can fit 11 to 14 pounds comfortably, and a king comforter should fit in it without overflowing or requiring cramming.
Front-loading washers can be loaded more snugly than top-loading ones. Some washing machines have a bulky cycle specifically for washing comforters and other bulky items. This cycle begins with a pre-soak period, which is followed by medium wash action. The pre-soak period allows the comforter to soak up water and detergent properly before agitation starts. Once the wash cycle is complete, a dryer with a capacity of 7 cubic feet or more can be used to dry the king comforter.