Adults usually grow up to the length of 91–152 cm (35.8-59.8 in). The longest to be reported was 189.2 cm (74.5 in) long. The large timber rattlesnakes weigh about 4.5 kg (9.9 Ib), but most weigh about 580-900 g (20-32 oz). Their scales are usually yellowish-brown or gray with dark brown or black stripes.