The weight of a “deer” is not a single number but reflects the vast biological diversity within the Cervidae family, which includes more than 60 species globally. Weights range from animals smaller than a house cat to those rivaling the size of a small car. This variability is a function of evolution adapting different species to dramatically different environments. Understanding deer weights requires looking at the extremes of this scale, from northern giants to diminutive species hiding in remote thickets.
Weight of Common North American Deer
The two most frequently encountered species in North America, the Whitetail Deer (Odocoileus virginianus) and the Mule Deer (Odocoileus hemionus), demonstrate significant size differences based on sex and geography. A mature Whitetail buck in the northern parts of its range, such as Minnesota or the Canadian provinces, typically weighs between 150 and 300 pounds. In these colder regions, some exceptional males have been recorded exceeding 400 pounds live weight, a size necessary for surviving harsh winters.
Whitetail deer in the southern US, such as those in Texas or Florida, are markedly smaller, with mature bucks averaging only 100 to 150 pounds. Females, or does, generally weigh between 88 and 198 pounds across the continent, with southern populations falling toward the lower end. Mule Deer, generally found west of the Missouri River, often possess a slightly heavier, more robust frame than their Whitetail cousins.
An adult Mule Deer buck typically weighs between 121 and 331 pounds, averaging around 203 pounds for a mature male. Females are considerably lighter, ranging from 95 to 198 pounds, with an average weight of about 150 pounds. Regional variations exist, such as the Sitka black-tailed deer subspecies of the Pacific Northwest, which is noticeably smaller than the Rocky Mountain Mule Deer, with males averaging only about 120 pounds.
The Massive Cervids: Elk and Moose
The Elk (Cervus canadensis) and the Moose (Alces alces) represent the upper limit of the deer family’s size in North America. Elk, the second-largest deer species globally, have adult bulls that typically weigh between 700 and 1,100 pounds, standing approximately five feet tall at the shoulder.
Elk cows are substantially smaller, typically weighing between 500 and 624 pounds. The Roosevelt Elk subspecies, found in the Pacific Northwest, is recognized as the largest in terms of body size, with some bulls estimated to reach up to 1,300 pounds. Despite their impressive mass, Elk are dwarfed by their larger relative, the Moose.
The Moose is the world’s largest and heaviest deer species. A mature bull Moose can weigh anywhere from 840 pounds to over 1,550 pounds, with the Alaskan Moose subspecies (Alces alces gigas) being the largest. The maximum recorded weight for a bull Moose is 1,808 pounds. Female Moose, or cows, are also immense, typically ranging from 595 to over 926 pounds.
Key Factors Influencing Deer Size
The broad weight ranges observed across and within deer species result from several interconnected biological and environmental variables. One significant influence is age class, as a deer must reach full maturity to achieve its maximum body size. Deer continue to grow for several years, often not reaching their peak skeletal and muscular mass until they are four to six years old.
Sexual dimorphism is another factor, referring to the consistent size difference between males and females. Males are significantly larger than females, a trait driven by evolutionary pressure for bucks to win dominance contests during the breeding season. The most powerful determinant of deer size is habitat quality and diet, which directly correlates to the availability of high-quality forage. Deer in areas with rich soil and abundant, protein-dense plants will grow larger than those in poor habitats.
Genetics and geography also play a defining role, often following Bergmann’s rule. This ecological rule suggests that animals in colder climates or higher latitudes tend to be larger than those of the same species in warmer regions. The larger body mass helps conserve heat more efficiently in northern deer, explaining the size difference between a Texas whitetail and one living in Canada.
Weight of the World’s Smallest Deer
At the opposite end of the weight spectrum from the Moose are the world’s smallest cervids, providing a contrast to the North American giants. The title of the smallest deer belongs to the Pudu, a genus consisting of two species native to South America. The Northern Pudu (Pudu mephistophiles) is the most diminutive, standing only about 13 to 14 inches tall at the shoulder.
These tiny deer weigh a mere 7.3 to 13.2 pounds when fully grown, making their mass comparable to that of a large rabbit. The Southern Pudu (Pudu puda) is only slightly larger, with adults typically weighing between 14 and 30 pounds. Other very small deer species include the Muntjac, or barking deer, of Asia, though they are generally heavier than the Pudu, with some species weighing around 25 pounds.