76″ x 80″ The king-size mattress dimensions are 76 inches wide by approximately 80 inches long – about 16 inches wider than a queen. This is the closest a couple can come to having as much personal space (38 inches) as each would have on a twin bed.
The recommended ideal room size for this bed would be 13 feet by 13 feet unless you want a cozy fit and prioritize bed size over anything else. Summary: King size beds are 76 inches by 80 inches which is a full 16 inches wider than a Queen.
*All Mattress Dimensions may vary by up to 2" due to varying factors including foam density, manufacturer design, compression or linen tolerances.