Before you consider the color, pattern, thickness and fiber content of a new comforter, make sure its dimensions are right for your king-size bed. King beds differ from other standard bed sizes in that there are two different kinds: wider and shorter eastern, or dual king beds; and slightly longer and narrower California, or western king beds. Choose the right one for a perfect fit.
Eastern or Dual King Beds
Eastern or dual king beds have mattresses measuring 78 inches wide and 80 inches long. A comforter to fit these king beds will generally be 102 inches in width, and range in length from 86 to 94 inches. Longer versions will hang farther off the end of the mattress, or can be pulled up toward the pillow end and folded over for extra plushness.
California or Western King Bed
A California or western king bed's mattress measures 72 inches in width and 84 inches in length. For the best fit, choose a comforter that's 86 to 102 inches wide and 94 to 102 inches long. If your mattress is extra deep -- greater than the standard 7 inches -- pick a longer, wider comforter that will cover it on all sides.