Grizzly bears are powerful animals, recognized as one of North America’s largest land carnivores. Their size commands attention. They roam diverse landscapes across the continent.
Measuring Grizzly Bear Size
Determining the “biggest” grizzly bear involves various measurements, as size can refer to several physical attributes. Weight is a common metric, with adult male grizzly bears typically weighing between 400 and 800 pounds, though some can reach up to 1,000 pounds. Females are generally smaller, weighing 300 to 400 pounds.
Beyond weight, measurements include body length, which averages between 56 to 88 inches from nose to tail. Shoulder height, measured on all fours, ranges from 36 to 46 inches for males and 30 to 38 inches for females. When standing on their hind legs, grizzlies can reach 8 to 9 feet. For official record-keeping, skull measurements are used to assess size.
Documented Large Grizzly Bears
The term “grizzly bear” refers to a subspecies of brown bear (Ursus arctos horribilis). Kodiak bears (Ursus arctos middendorffi), found on the Kodiak Archipelago, are the largest subspecies of brown bear and can be larger than mainland grizzlies. Kodiak bears average over 1,500 pounds and can stand eight to ten feet tall on their hind legs, with some males exceeding 1,500 pounds. A captive Kodiak bear named Clyde reportedly weighed 2,130 pounds when he died in 1987. The largest brown bear ever recorded, a 1,656-pound Kodiak, was captured in Alaska in 1894.
For mainland grizzly bears, the world record skull was discovered near Lone Mountain, Alaska, in 1976 by Gordon E. Scott, measuring 27 13/16 inches. This bear was estimated to have weighed around 1,200 pounds. A new record for a hunter-killed grizzly was set in September 2024 by Brian van Lanen, whose bear’s skull measured 27 9/16 inches. Another hunter-killed grizzly was taken by Larry Fitzgerald in 2013, with a skull scoring 27 6/16 inches. Anecdotal reports of a grizzly weighing over 1,600 pounds killed by a US Forest Service worker are difficult to verify compared to official skull records.
Factors Contributing to Grizzly Bear Size
Several environmental and biological factors influence grizzly bear size. Diet plays a role, with bears in coastal regions, particularly those with abundant salmon, tending to be larger than inland grizzlies. The high fat content of salmon provides a rich energy source that supports greater growth. Inland bears, whose diets are often more plant-based, do not achieve the same maximum sizes.
Habitat quality, including diverse food resources, also impacts bear size. Genetics and age are factors, as males grow larger than females and continue to increase in size throughout their lives. Regional variations in climate and productivity can also influence growth, with smaller bears found in colder, less productive environments. Island gigantism, where isolated populations evolve to be larger due to specific environmental conditions and lack of competition, contributes to the immense size of Kodiak bears.