The booted eagle is a medium-sized eagle, measuring 40 to 50 cm in length and weighing 500 to 750 grams. The female eagles are larger and weigh 850 to 1,250 grams. The wingspan is 110 to 140 cm. There are two distinct colour morphs, with several intermediate plumages. The pale morphs are mainly light grey. They have a darker head and flight feathers. The dark morphs have dark brown plumage with dark greyish flight feathers. The call is a shrill kli-kli-kli sound.