The sable antelope is sexually dimorphic, with the male heavier and about one-fifth taller than the female.The head-and-body length is typically between 190 and 255 cm (75 and 100 in).[13] Males reach about 117–140 cm (46–55 in) at the shoulder, while females are slightly shorter. Males typically weigh 235 kg (518 lb) and females 220 kg (490 lb). The tail is 40–75 cm (16–30 in) long, with a tuft at the end.

The sable antelope has a compact and robust build, characterized by a thick neck and tough skin. It has a well-developed and often upright mane on its neck, as well as a short mane on the throat.Its general colouration is rich chestnut to black. Females and juveniles are chestnut to dark brown, while males begin darkening and turn black after three years. However, in southern populations, females have a brown to black coat. Calves less than two months old are a light tan and show faint markings.The underparts, cheek, and chin are all white, creating a great contrast with the dark back and flanks.Long, white hairs are present below the eyes, and a wide, black stripe runs over the nose.