At just in head-and-body length and weighing about , the feathertail glider is only around the size of a small mouse, and is the world's smallest gliding mammal. The fur is soft and silky, and is a uniform greyish brown on the upper body, and white on the underside. There are rings of dark fur around the eyes, the rhinarium is hairless and deeply cleft, and the ears are moderately large and rounded. The glider also has an unusually large number of whiskers, sprouting from the snout and cheeks, and from the base of each ear.