California king mattresses are designed for tall sleepers, measuring 72 inches wide by 84 inches long—making them the longest standard mattress size. They provide extra legroom while still offering ample width for couples. This size is ideal for larger master bedrooms and those over 6 feet tall who find regular king or queen mattresses too short. California kings also add a luxurious feel to the bedroom and can accommodate pets sleeping at the foot of the bed.