The common night adder can grow up to around 60 centimeters (24 in) long, making it the longest species of the genus "Causus". The longest ever recorded was a male found in eastern Zimbabwe which was 93 centimeters (around 37 in) long. They are usually olive green, brown, or grayish-brown in color with black rhombic-shaped blotches, but not all have blotches on them.