The powerful owl is a large owl with a relatively small head and a rounded tail. It is dark grey to dark grey-brown above, with white barring, and off-white below, with distinctive dark V-shaped chevrons. The eyes are yellow, set in a dark grey/brown facial mask. The legs are feathered and the yellow to orange feet are massive, with sharp talons. The sexes are alike but the female is smaller, with a narrower head. Juvenile birds are downy white on the head and underparts, the underparts are sparsely streaked, and they have much shorter tails than the adults. Powerful owls are the largest of the Australian nocturnal birds (night birds).