Pectoral fin length is about 40 cm, and expanse of the flukes is about 61 cm.
Males are generally larger and heavier than females.
The head is only about one-sixth the total length and resembles that of some delphinid genera in external outline, but the blunt snout projects beyond the lower jaw. Among cetaceans, the facial part of the skull of Kogia is among the shortest. The blowhole of Kogia, like that of Physeter, is on the left side of the head, but it is located on the forehead rather than toward the tip of the snout. Kogia resembles Physeter in having a spermaceti organ in the head and in having the functional teeth confined to the lower jaw. A few smaller, nonfunctional teeth may be present in the upper jaw of K. simus.