How tall can a human being theoretically be?

Theoretically, a human being can reach a maximum height of around 7 feet, 9 inches (2.3 meters) if they are fully grown. This is based on the average height of a male adult in the United States. According to the Guinness Book of World Records, the tallest man was Sultan Kösen. Sultan Kösen (born 10 December 1982) is a Turkish farmer of Kurdish ethnicity who holds the Guinness World Record for tallest living male at 251 cm (8 ft 2.82 in). Kösen's growth resulted from the conditions gigantism and acromegaly, caused by a tumor affecting his pituitary gland.