Polar Bears (Ursus maritimus) and Brown Bears (Ursus arctos) are the two largest land carnivores on Earth. While the Polar Bear is generally bigger, the comparison is complex. Polar bears hold the title for the largest bear species on average. However, the Brown Bear species encompasses a massive range of sizes, including a subspecies that can occasionally match the largest polar bears.
The Dimensions of Polar Bears
The Polar Bear, a marine mammal uniquely adapted to the Arctic, establishes the benchmark for size among the world’s bears. Adult male polar bears exhibit significant size differences compared to females, a trait known as sexual dimorphism. Males typically range in body length from 6.6 to 8.2 feet (200 to 250 cm) and stand between 4.3 and 5.2 feet (130 to 160 cm) tall at the shoulder.
Their weight consistently places them at the top of the size spectrum for land predators. Males commonly weigh between 660 and 1,760 pounds (300 to 800 kg). Females are smaller, generally measuring 5.9 to 6.6 feet (180 to 200 cm) in length and weighing 330 to 660 pounds (150 to 300 kg). The largest recorded male polar bear, shot in Alaska in 1960, reportedly weighed 2,209 pounds (1,002 kg).
These Arctic giants maintain a relatively consistent size across their circumpolar range, due to a specialized, high-fat diet of seals. Their body structure is slightly more streamlined than a brown bear’s, featuring a longer neck and a narrower, flatter skull. They lack the prominent shoulder hump characteristic of their brown bear relatives.
Size Variation Among Brown Bears
The Brown Bear (Ursus arctos) represents a species with one of the most dramatic ranges of size among all large mammals. The species includes many different subspecies and populations, which vary greatly depending on their geographic location and food availability. Inland populations, often referred to as Grizzly Bears (Ursus arctos horribilis), typically inhabit areas with scarcer food resources, resulting in a smaller average size.
A typical adult male Grizzly Bear weighs around 400 to 790 pounds, standing about 3.3 feet (1 meter) tall at the shoulder. These inland bears are generally smaller than their coastal counterparts because their diet relies more on vegetation, roots, and smaller animals. In contrast, the largest Brown Bear subspecies are found along the coast, where access to protein-rich seasonal salmon runs fuels their immense growth.
The Kodiak Bear (Ursus arctos middendorffi), isolated on the Kodiak Archipelago in Alaska, is the prime example of coastal gigantism. Adult male Kodiak Bears commonly weigh between 600 and 1,400 pounds (272 to 635 kg). Mature individuals average over 1,000 pounds (477 to 534 kg) when at their heaviest in the fall. These bears can stand over 10 feet (3 meters) tall on their hind legs and are structurally bulkier than a polar bear, possessing a distinct muscular hump above their shoulders.
Head-to-Head Comparison of Dimensions
When comparing the average size of the two species, the Polar Bear is generally the larger animal. An average adult male Polar Bear weighs approximately 990 pounds (450 kg), which is significantly more than most inland Brown Bears. The Polar Bear’s overall consistency in size across its range, due to its specialized diet of calorie-dense seal blubber, solidifies its position as the largest bear species by average mass.
However, the size comparison becomes much closer when focusing on the largest subspecies of Brown Bear, the Kodiak Bear. While the Polar Bear is typically longer and taller, the largest Kodiak Bears can rival or even occasionally exceed the weight of an average male Polar Bear. Mature Kodiak males can reach maximum weights of around 1,500 pounds (680 kg) in the wild, placing them very close to the heavier end of the Polar Bear range.
The single heaviest bear ever recorded was a Polar Bear at over 2,200 pounds, but the largest wild Kodiak Bear on record weighed 1,656 pounds (751 kg). Therefore, based on average adult male size and overall body length, the Polar Bear is considered the largest land carnivore.