Like other dolphins of the genus Stenella, spinner dolphins are relatively small, reaching lengths of 6 to 7 feet (2 m) and weighing approximately 130 to 170 pounds (59-77 kg) at adulthood. They have long, slender snouts or beaks. There is a great deal of color variation depending on the region.

Spinner dolphins are best known for their above-water displays of leaping and spinning several times on their body axis. Leaps can often be done in a series with as many as 14 leaps in a row. Spinner dolphins are sometimes found in associations with bottlenose dolphins or humpback whales in Hawaii, which may benefit one or both species.