The bullfrog is the largest frog in North America, ranging from 3.5 to 8 inches long. The color is shades of green to brownish above with random mottling of darker gray. There is a large external eardrum (larger in males than in females) on the side of the head. The hind feet are fully webbed except for the last joint of the longest toe. The belly is cream to white, and may be mottled gray.