(1) 1200 - 1300 gm Explanation: The adult human brain weighs on average about 3 lbs. (1.5 kg) with a volume of around 1130 cubic centimetres (cm3) in women and 1260 cm3 in men, although there is substantial individual. variation. Men with the same body height and body surface area as women have on average 100g heavier brains, although these differences do not correlate in any simple way with IQ or other measures of cognitive performance. The human brain has the same general structure as the brains of other mammals, but is larger than any other in relation to body size.