King vs. California King mattress . . . what's the difference? Size! At 76 by 80 inches, a king mattress is perfect for the average couple; however, the extra 4 inches on the California king can be a game-changer for anyone over 6 feet tall. Wondering if a king mattress is right for you? Message BoxDrop Mattress of Norfolk or give us a call today by clicking on the button below.