The weight of the average squirrel is approximately 1 pound with a length of 18 inches. The 1/2-ounce African pygmy squirrel is the smallest squirrel in the world. The largest known squirrel is the 20-inch-long hoary marmot. The hoary marmot also has an average weight of 20 pounds.
Squirrel body types and average weights are further determined by their chosen habitats. Ground squirrels are short and stocky, tree squirrels are lean, and flying squirrels are small and light. The black giant squirrel weighs around 3 pounds and is 100 times the size of the African pygmy. There are 279 different species in the family Sciuridae.