Brown bears have very large and curved claws, those present on the forelimbs being longer than those on the hind limbs. They may reach 5 to 6 centimetres (2.0 to 2.4 in) and sometimes 7 to 10 centimetres (2.8 to 3.9 in) along the curve. They are generally dark with a light tip, with some forms having completely light claws. Brown bear claws are longer and straighter than those of American black bears. The claws are blunt, while those of a black bear are sharp.
Adults have massive, heavily built concave skulls, which are large in proportion to the body. The forehead is high and rises steeply. The projections of the skull are well developed when compared to those of Asian black bears: the latter have sagittal crests not exceeding more than 19–20% of the total length of the skull, while the former have sagittal crests comprising up to 40–41% of the skull's length.
Skull projections are more weakly developed in females than in males. The braincase is relatively small and elongated. There is a great deal of geographical variation in the skull, and presents itself chiefly in dimensions. Grizzlies, for example, tend to have flatter profiles than European and coastal American brown bears. Skull lengths of Russian bears tend to be 31.5 to 45.5 centimetres (12.4 to 17.9 in) for males, and 27.5 to 39.7 centimetres (10.8 to 15.6 in) for females. The width of the zygomatic arches in males is 17.5 to 27.7 centimetres (6.9 to 11 in), and 14.7 to 24.7 centimetres (5.8 to 9.7 in) in females.
Brown bears have very strong teeth: the incisors are relatively big and the canine teeth are large, the lower ones being strongly curved. The first three molars of the upper jaw are underdeveloped and single crowned with one root. The second upper molar is smaller than the others, and is usually absent in adults. It is usually lost at an early age, leaving no trace of the alveolus in the jaw. The first three molars of the lower jaw are very weak, and are often lost at an early age. Although they have powerful jaws, brown bear jaws are incapable of breaking large bones with the ease of spotted hyenas.
The dimensions of brown bears fluctuate very greatly according to sex, age, individual, geographic location, and season. The normal range of physical dimensions for a brown bear is a head-and-body length of 1.7 to 2.8 meters (5.6 to 9.2 ft) and a shoulder height of 90 to 150 centimeters (35–60 in). The smallest subspecies is the Eurasian brown bear, whose mature females weigh as little as 90 kg (200 lb). Barely larger, grizzly bears from the Yukon region (which are a third smaller than most grizzlies) can weigh as little as 100 kg (220 lb) in the spring and the Syrian brown bear, with mature females weighing as little as 150 kg (330 lb).
The largest subspecies are the Kodiak bear, Siberian brown bear, and the bears from coastal Russia, Alaska, and British Columbia. It is not unusual for large males in coastal regions to stand over 3 m (9.8 ft) while on their hind legs, and to weigh up to 680 kg (1,500 lb). The heaviest recorded brown bear weighed over 1,150 kilograms (2,500 lb). Brown bears have long, thick fur, with a moderately long mane at the back of the neck. In India, brown bears can be reddish with silver tips, while in China, brown bears are bicolored with a yellow-brown or whitish cape across the shoulders.
North American grizzlies can be dark brown (almost black) to cream (almost white) or yellowish brown. Black hairs usually have white tips. The winter fur is very thick and long, especially in northern subspecies, and can reach 11 to 12 centimetres (4 to 5 in) at the withers. The winter hairs are thin, yet rough to the touch. The summer fur is much shorter and sparser, and its length and density varies geographically.