Reptiles are vertebrates characterized by ectothermic metabolism, meaning they rely on external heat sources to regulate body temperature. Their bodies are typically covered in scales or scutes, and they reproduce primarily by laying eggs, though some species give birth to live young. Determining the single “biggest” reptile is complex because size can be measured by either length or mass. The largest living species often holds the title for both, making the saltwater crocodile the definitive answer.
The Reigning Champion: Saltwater Crocodile
The largest living reptile is the saltwater crocodile (Crocodylus porosus), which dominates the Indo-Pacific region. This apex predator is the most massive and longest of all extant reptile species. Adult males routinely reach lengths of 5 to 6 meters (16.4 to 19.7 feet) and weigh between 1,000 and 1,500 kilograms (2,200 to 3,300 pounds).
Specimens exceeding 6.3 meters (20.7 feet) are rare, but a confirmed record exists for an individual measuring 6.32 meters in length and weighing approximately 1,360 kilograms (3,000 pounds). Unverified reports suggest some males may approach 7 meters (23 feet) in size, with a mass of up to 2,000 kilograms (4,400 pounds). Its powerful jaws deliver the strongest recorded bite force in the animal kingdom today.
The saltwater crocodile is found across a vast range, including brackish estuaries, mangrove swamps, and coastal waters from India through Southeast Asia and down to Northern Australia. Its size allows it to prey on nearly any animal that enters its territory. This scale establishes it as the largest terrestrial and riparian predator on Earth.
Largest Reptiles By Classification
While crocodilians hold the overall size record, other major reptilian orders feature their own giants. Among the squamates (snakes and lizards), the size distinction is split between length and mass. The reticulated python (Malayopython reticulatus) holds the record for the world’s longest snake, with verified specimens exceeding 6.25 meters (20.5 feet).
The green anaconda (Eunectes murinus) is the heaviest snake, with a bulkier body that can weigh over 227 kilograms (500 pounds). Though shorter than the reticulated python, a 5.2-meter anaconda can weigh as much as a 7.3-meter python due to its girth. The Komodo dragon (Varanus komodoensis) is the largest living lizard species, reaching up to 3.13 meters (10.3 feet) in length and a maximum weight of 166 kilograms (366 pounds).
The order Testudines (turtles and tortoises) is represented by the leatherback sea turtle (Dermochelys coriacea). This marine giant is the heaviest non-crocodilian reptile. Adult males average 1.83 to 2.2 meters (6 to 7.2 feet) in length and weigh between 250 and 700 kilograms (550 to 1,540 pounds).
Size Comparisons with Extinct Giants
The scale of today’s largest reptiles pales in comparison to the sizes achieved by certain extinct species. The prehistoric crocodyliform Sarcosuchus imperator, nicknamed SuperCroc, provides a stark contrast to its modern relatives. Living around 110 million years ago, this ancient reptile is estimated to have reached lengths of 9 to 9.5 meters (29.5 to 31.2 feet).
The mass of Sarcosuchus is estimated to have been between 3.45 and 4.3 metric tons (3,800 to 4,700 kilograms), which is more than four times the average weight of a modern saltwater crocodile. The extinct snake Titanoboa cerrejonensis was the largest serpent known, reaching an estimated length of 13 meters (42 feet) and weighing over 1,135 kilograms (2,500 pounds).