The largest sea turtle species is the leatherback sea turtle. They can grow to an average length of 1.5 to 2 meters (4.9 to 6.6 feet) and weigh between 300 to 700 kilograms (660 to 1,540 pounds). The largest verified leatherback sea turtle measured about 2.56 meters (8.4 feet) long and weighed around 916 kilograms (2,019 pounds). Some reports suggest they can weigh up to 1,000 kilograms (2,200 pounds) or even more, with occasional accounts of leatherbacks reaching as much as 2,000 pounds (900 kilograms) in weight and lengths over 6 feet.

Other species of sea turtles are smaller, generally ranging from about 2 to 4 feet in length and weights between 100 to 500 pounds, but the leatherback holds the record for the biggest size among sea turtles.