As the name suggests, the eastern gray squirrel has predominantly gray fur but it can have a reddish color. It has a white underside and a large bushy tail. Particularly in urban situations where the risk of predation is reduced, both white and black colored individuals are quite often found. The melanistic form, which is almost entirely black, is predominant in certain populations and in certain geographic areas, such as in large parts of southeastern Canada. There are also genetic variations within these, including individuals with black tails and black colored squirrels with white tails. The head and body length is from 23 to 30 cm, the tail from 19 to 25 cm and the adult weight varies between 400 and 600 grams.

The tracks of an eastern gray squirrel are difficult to distinguish from its cousins the fox squirrel and Abert’s Squirrel, though the latter’s range is almost entirely different from the Gray’s. Like all squirrels, the Eastern Gray shows four fingers on the front feet and five on the hind feet. The hind foot-pad is often not visible in the track. When bounding or moving at speed, the front foot tracks will be behind the hind foot tracks. The bounding stride can be two or three feet long.