With the exception of the flying squirrel, North American red squirrels are the smallest species of tree squirrel in North America. The squirrel measures about 30 cm (approx. 12 inches) from the nose to the tip of the tail and weighs about 225g (approx. 8 ounces). The fur on the back and sides of the red squirrel is brownish-red and the underparts are white with a black stripe separating the two colors. The ear tufts and the limbs are also brownish-red. They have a prominent white eye ring and the tail is brownish-red above and grey with white flecks below.
While the Mt Graham red squirrel subspecies exhibits only slight phenotypic differences (slightly smaller body size and slightly narrower skull) than other red squirrels found in North America, genetic evidence does support the distinction of this subspecies (Sullivan and Yates. 1994. Storm over a Mountain Island. University of Arizona Press, Tucson, AZ).