Standard king size comforters measure 102 inches wide by 86 to 88 inches long. To accommodate the extra length of a Cal king mattress, these beds need a bedspread that measures at least 96 to 98 inches long. Larger comforters designed for a Wyoming king mattress (84 inches by 84 inches) can also be found online. These comforters measure 96 inches wide by 108 inches long and are often called “oversized” king comforters.