Adult western diamondback rattlesnakes usually grow up to the length of 120 cm (3.9 ft), but some grow up to the length of 150 cm (4.9 ft) and 180 cm (5.9 ft). The longest ever found was 213 cm (6.99 ft) long. Males are much larger than females, but they become larger when they mature. These rattlesnakes usually weigh about 1.8 to 2.7 kg (4.0 to 6.0 Ib), but some can weigh 6.7 kg (15 Ib).They are usually gray-brown in color, but some are pinkish brown, or brick red. It is then covered with dark gray-brown blotches and white stripes.