This list of largest reptiles takes into consideration both body length and mass of large reptile species, including average ranges and maximum records. The crocodilians reach a length of and a mass of or more. It is worth mentioning that, unlike the upper weight of mammals, birds or fish, mass in reptiles is frequently poorly documented, thus subject to conjecture and estimation.
The saltwater crocodile is considered to be the largest extant reptile, verified at up to in length and around in mass. Larger specimens have been reported albeit not fully verified, the maximum of which is purportedly long with an estimated mass of .
The following table below lists the 15 largest extant reptile species ranked according to their average mass range, with maximum reported/reliable/estimated mass also being provided.
Overall Rank Species Image Mass range [kg] Maximum mass [kg] Maximum length [m] 1 Saltwater crocodile 400 – 1,300 2,000 7 2 Nile crocodileBrazaitis, P. (1989). The forensic identification of crocodilian hides and products. In: Crocodiles: Their Ecology, Management, and Conservation. IUCN Special Publication of Crocodile Specialist Groups of the Species Survival Commission. pp. 17–43.Graham, A. D. (1968). The Lake Rudolf Crocodile (Crocodylus niloticus Laurenti) Population. Masters of Science Thesis, The University of East Africa. 250 – 900 1,090 6.5 3 American crocodile 150 – 600 1,283 7 4 Orinoco crocodile 200 – 700Orinoco crocodile videos, photos and facts – Crocodylus intermedius . ARKive 1,100 7 5 Black caiman 300 – 500French Guiana. kwata.net (2003). 1,100 6Black Caiman, Black Caiman Skull. Dinosaurcorporation.com. Retrieved on 2012-08-23.Crocodilian Species – Black Caiman (Melanosucus niger). Crocodilian.com. Retrieved on 2012-08-23. 6 American alligator 200 – 500 1,000 5.8 7 Gharial 160 – 680 1,000Gavials (Gharials), Gavial (Gharial) Pictures, Gavial (Gharial) Facts. Animals.nationalgeographic.com 7 8 Leatherback sea turtle 200 – 500Leatherback Sea Turtle. euroturtle.org 961.1 3 9 False gharial 100 – 590 800 7 10 Mugger crocodile 160 – 450 700 5.63 11 Slender-snouted crocodile 125 - 325 667 4.5 12 Loggerhead sea turtle 100 – 350 545 2.1 13 Green sea turtle 100–320 500 1.8 14 Galapagos tortoise 150 – 300ADW: Geochelone nigra: Information. Animaldiversity.ummz.umich.edu 417 1.8 15 Aldabra giant tortoise 132 – 250 360 1.5
Lizards and snakes (Squamata) Snakes
The most massive living member of this highly diverse reptilian order is the green anaconda (Eunectes murinus) of the neotropical riverways. These may exceed and , although such reports are not fully verified. Rumors of larger anacondas also persist.Green Anacondas, Green Anaconda Pictures, Green Anaconda Facts. Animals.nationalgeographic.com The reticulated python (Malayopython reticulatus) of Southeast Asia is longer but more slender, and has been reported to measure as much as in length and weigh up to .Cotswold Wildlife Park and Gardens | Reticulated python. Cotswoldwildlifepark.co.uk The Burmese python, a south-east Asian species is known to reach up to and weigh as much as and is generally among the three heaviest species of snakes. Several other species of python can reach or exceed in length and in weight. Fossils of what may be the largest snake ever, the extinct boa Titanoboa were found in coal mines in Colombia. It has been estimated to reach a length of and weighed about . Length estimates for another very long extinct snake, the madtsoiid Vasuki indicus of India, range from .
Among the colubrids, the most diverse snake family, the largest snake may be the keeled rat snake (Ptyas carinata) at up to . The Indian rat snake (Ptyas mucosa) is also very large with maximum sizes of up to , making it the second-largest species in the genus Ptyas.Auliya, M. (2010). Conservation Status and Impact of Trade on the Oriental Rat Snake Ptyas mucosa in Java, Indonesia. TRAFFIC Southeast Asia.Das, I. (2015). A field guide to the reptiles of South-East Asia. Bloomsbury Publishing. The Tiger rat snake (Spilotes pullatus), which usually grows to about , has been reported to reach up to , ranking it among the largest colubrids. The genus Drymarchon also contains some of the largest colubrids such as the Eastern indigo snake and the indigo snake (Drymarchon corais) which can both reach lengths of more than . Few other species in the colubrid family (such as False water cobra, Brown tree snake and Pseustes sulphureus) can reach lengths of , but they are relatively slender and generally do not exceed in weight.
The longest venomous snake is the king cobra (Ophiophagus hannah), with lengths (recorded in captivity) of up to and a weight of up to . It is also the largest elapid. The second-longest venomous snake in the world is possibly the African black mamba (Dendroaspis polylepis), which can grow up to . Among the genus Naja, the longest member arguably may be the forest cobra (Naja melanoleuca), which can reportedly grow up to . The King brown snake, reaching lengths of up to and weights of or more, is the largest venomous snake in Australia. The Yellow sea snake (Hydrophis spiralis) is the largest of the sea snakes growing up to a length of . Few other elapids can reach or exceed in length and in weight.
The Gaboon viper, a very bulky species with a maximum length of around , is typically the heaviest non-constrictor snake and the biggest member of the viper family, with unverified specimens reported to as much as .Gaboon Viper, Bitis gabonica . California Academy of Sciences The Eastern diamondback rattlesnake is nearly as large, with the maximum length being and maximum weight being . The rattlesnake genus Crotalus, which includes the aforementioned eastern diamondback rattlesnake and western diamondback rattlesnake (Crotalus atrox), reaches a maximum length of , and according to W. A. King one large specimen had a length of and a mass of . The third largest rattlesnake is the Mexican west coast rattlesnake (Crotalus basiliscus), which reaches long and mass, and one captive-raised male was weighed at in 2020. While not quite as heavy, other members of the viper family are longer still, the South American bushmaster (Lachesis muta) and Central American bushmaster (Lachesis stenophrys), with a maximum length in the range of , with the former being considered as the third-longest venomous snake in the world.Mehrtens JM. 1987. Living Snakes of the World in Color. New York: Sterling Publishers. .
Lizards
The largest of the monitor lizards (and the largest extant lizard in genera) is the Komodo dragon (Varanus komodoensis), endemic to the island of its name, at a maximum size of long and , although this is currently the only record that places the mass above . Crocodile monitor (Varanus salvadorii) is probably the longest extant lizard, known to grow as much as , with reported lengths of up to and weights of up to . The Asian water monitor is also one of the largest lizards in the world, with sizes of up to and reported weights of up to . Few other species (such as perentie and nile monitor) can reach or possibly exceed in length and in weight. The prehistoric Australian megalania (Varanus priscus), which may have existed up to 40,000 years ago, is the largest terrestrial lizard known to exist, but the lack of a complete skeleton has resulted in a wide range of size estimates. Molnar's 2004 assessment resulted in an average weight of and length of , and a maximum of at in length, which is toward the high end of the early estimates.
Iguanas are very large lizards, some of which can reach lengths of up to 2 m (6.6 ft) and weigh more than . They are the largest lizards after some large species of monitor lizards, and the largest lizards in the New World. Iguanas vary considerably in size and form, but even the smallest lizards in this family are still quite large. Many sources describe the green iguana (Iguana iguana) as the largest iguanid, often reaching lengths up to 1.5 metres (4.91 ft) and masses of ,Rivas, J.A. (2008). Pers. comm. and with a maximum length of 2 m (6.6 ft) and a mass of and in some cases even . However, the heaviest species in this family is the blue iguana (Cyclura lewisi), with a total length of up to 1.5 m (4.91 ft), a SVL of 51–76 cm (30 in) and a mass of up to It is the eighth-heaviest and largest extant lizard. Other large species in this family include the Galapagos land iguana (Conolophus subcristataus), with a length of about 1.5 m (4.91 ft) and a mass of up to . It is the second-heaviest iguanid after the blue iguana and the ninth-heaviest and largest lizard in the world. Another large species from the same genus is the Santa Fe land iguana (Conolophus pallidus), reaching a SVL of and a mass of . The Galapagos pink land iguana (Conolophus marthae) have snout-vent length and the mass of .. The marine iguana (Amblyrhynchus cristatus) is also among the largest iguanas in the world, and the largest reptile on Galapagos Islands after the Galapagos land iguana, not including turtles reaching a maximum total length of 1.4 m (4.59 ft), a SVL of from 12 till 56 cm (from 4.72 till 22 in) and a mass of from Endangered animals of the world pp. 48 depending on islands. The largest extant gecko is the New Caledonian giant gecko (Rhacodactylus leachianus) of New Caledonia, which can grow to 14 inches in length.Allison Ballance and Rod Morris, "Island Magic; wildlife of the south seas", David Bateman publishing, 2003 It was surpassed in size by the extinct Kawekaweau (Hoplodactylus delcourti) of New Zealand, which grew to a length of .
Mosasaurs
The largest members of this order were the giant mosasaurs (including Hainosaurus, Mosasaurus, and Tylosaurus), which grew to around and were projected to weigh up to .Science & Nature – Sea Monsters – Fact File: Giant Mosasaur. BBC (2005-08-26)
Tuataras (Sphenodontia) The larger of the two extant species of the New Zealand native tuataras is the Brothers Island tuatara (Sphenodon guntheri). The maximum size is and .
Ichthyosaurs (Ichthyosauria)
Some of these marine reptiles were comparable in size to modern cetaceans. Until 2024, the largest ichthyosaur was believed to be the Late Triassic species Shastasaurus sikanniensis, at approximately long and in weight, from the Norian stage in what is now British Columbia. However, in 2018, a specimen from the Rhaetian stage of Lilstock was discovered to be 25 percent larger, approximately in length. The specimen was referred in 2024 to Ichthyotitan severnensis, with revised estimates of making it the largest known marine reptile. Shonisaurus popularis is another enormous ichthyosaur. It reached in length and in weight. Cymbospondylus youngorum is the largest Middle Triassic ichthyosaur, with in length and in weight. In 2022 the tooth of a giant predatory ichthyosaur (unofficially named Swiss Tyrant) was discovered in the Swiss Alps. Based on crown diameter, the animal was about long and weighed , making it one of the largest marine reptiles ever.
Pantestudines Turtles and tortoises (Testudines)
The largest extant turtle is the leatherback sea turtle (Dermochelys coriacea), reaching a maximum total length of and a weight of . The second-largest extant testudine is the Loggerhead sea turtle. It tends to weigh slightly more on average than the green sea turtle, and reaches more massive top sizes. The Loggerhead sea turtle (Caretta caretta) reaches a maximum size of and weight of , while the Green sea turtle (Chelonia mydas) reaches a maximum weight in the range of . The Flatback sea turtle (Natator depressus) may reach a weight of up to . Other species of Sea turtles are small-medium in size, but are still considered as large-sized for a typical turtle.