In the United States, the Alaskan king bed is the largest mattress available. These beds measure 108 inches wide by 108 inches long. Alaskan kings are not readily available and often require a custom-made frame. King beds are more common and are 16 inches wider than a queen. Larger couples or those who prefer to co-sleep with their children may sleep more comfortably on a king mattress. Taller sleepers (those 6 feet and up) may prefer a California king mattress. These beds are 4 inches longer than both a standard king and a queen bed.