The Asian forest tortoise is the largest tortoise in mainland Asia. The largest adults of the northern subspecies, Manouria emys phayrei, can reach 25 kg (55 lb) in the wild and much more than that in captivity.
The carapace is considerably depressed, its depth not half its length; anterior and posterior margins reverted, more or less strongly serrated; nuchal present; two supracaudal shields; dorsal shields concentrically striated, often concave; vertebrals much broader than long and at least as broad as costals. The plastron is large, gular region somewhat produced and usually notched, hind lobe deeply notched; the pectoral shields may be widely separated from each other, or from a short median suture; axillary shield very small, inguinal large. The head is moderate in size; two large prefrontal shields and a large frontal; beak not hooked; jaws feebly denticulated, the alveolar surface of the upper jaw with a strong median ridge. The forelimbs anteriorly have very large, bony, pointed, imbricate tubercles, forming four or five longitudinal series. The hind limbs have very large bony tubercles on the plantar surface, with others larger, conical, and spur-like on the heel, and a group of still larger conical tubercles on each side on the back of the thighs. Adults are dark brown or blackish. The carapace of juveniles is yellowish brown, with dark-brown markings.