List of largest snakes

The largest living snakes in the world, measured either by length or by weight, are various members of the Boidae and Pythonidae families. They include anacondas, pythons and boa constrictors, which are all non-venomous constrictors. The longest venomous snake, with a length up to 18.5 - 18.8 ft, is the king cobra, while contesters for the heaviest title include the Gaboon viper and the Eastern diamondback rattlesnake. All of these three species reach a maximum mass in the range of 6 - 20 kg.

There are fourteen or fifteen living snake species that clearly have a maximum mass of at least 50 lb, as shown in the table below. Whether the number is fourteen or fifteen depends on whether a DNA analysis reported in 2024 results in the recognition of the northern green anaconda ("Eunectes akayima", listed in row 1b below) as a species distinct from the ordinary (southern) green anaconda (Eunectes murinus). These include all species that reach a length of at least 20 ft. There are also two other species that reach nearly this length – the Oenpelli python (binomial name Nyctophilopython oenpelliensis, Simalia oenpelliensis or Morelia oenpelliensis), and the olive python (Liasis olivaceus). The information available about these two species is rather limited. The Oenpelli python, in particular, has been called the rarest python in the world.

It is important to be aware that there is considerable variation in the maximum reported size of these species, and most measurements are not truly verifiable, so the sizes listed should not be considered definitive. In general, the reported lengths are likely to be somewhat overestimated. In spite of what has been, for many years, a standing offer of a large financial reward (initially $1,000 offered by U.S. President Theodore Roosevelt in the early 1900s, later raised to $5,000, then $15,000 in 1978 and $50,000 in 1980) for a live, healthy snake over 30 ft long by the New York Zoological Society (later renamed as the Wildlife Conservation Society), no attempt to claim the reward has ever been made.

Although it is generally accepted that the reticulated python is the world's longest snake, most length estimates longer than 6 m have been called into question. It has been suggested that confident length records for the largest snakes must be established from a dead body soon after death, or alternatively from a heavily sedated snake, using a steel tape and in the presence of witnesses, and must be published (and preferably recorded on video). At least one reticulated python was measured under full anesthesia at 6.95 m, and somewhat less reliable scientific reports up to 10.05 m have appeared.

Although weight is easier to measure reliably than length (e.g., by simply measuring the weight of a container with and without the snake inside it and subtracting one measurement from the other), a significant factor in the weight of a snake is whether it has been kept in captivity and provided an unusual abundance of food in conditions that also cause reduced levels of activity. Moreover, the weight of wild specimens is often reduced as a symptom of parasite infestations that are eliminated by veterinary care in captivity. Thus, the largest weights measured for captive specimens often greatly exceed the largest weights observed in the wild for the same species. This phenomenon may particularly affect the weight measurements for anaconda species that are especially difficult to keep in captivity due to their semi-aquatic nature, resulting in other species having larger weights measured in captivity. In particular, the green anaconda (Eunectes murinus) is an especially massive snake if only observations in the wild are considered.

Boas (Boidae)

 * The most massive living member of this highly diverse reptilian order is the green anaconda (Eunectes murinus) of the neotropical riverways. These may exceed 8.8 m and 227 kg, although such reports are not fully verified. Rumors of larger anacondas also persist. The reticulated python (Python reticulatus) of Southeast Asia is longer but more slender, and has been reported to measure as much as 10 m in length and to weigh up to 158 kg.

Typical snakes (Colubridae)

 * Among the colubrids, the most diverse snake family, the largest snakes may be the keeled rat snake (Ptyas carinata) at up to 4 m. The genus Drymarchon also contains some of the largest colubrids such as the eastern indigo snake (Drymarchon couperi) and the indigo snake (Drymarchon corais) which can both reach lengths of almost 3 m. The first one mentioned may grow to 5 kg and more.
 * Another large species in this family is the false water cobra (Hydrodynastes gigas) reaching a length of 3 m, and a mass of 4.56 kg, one of the largest venomous snakes in South America. The tiger rat snake (Spilotes pullatus), also living in South America, can reach a length of 2.7 m. The yellow-bellied puffing snake (Pseustes sulphureus) can exceed a length of 3 m.
 * The largest racer, the Hispaniola racer (Haitiophis anomalus), at an average length of 2 m, is the longest snake species in the West Indies.

Elapids (Elapidae)

 * The longest venomous snake is the king cobra (Ophiophagus hannah), with lengths (recorded in captivity) of up to 5.7 m and a weight of up to 12.7 kg. 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 4.5 m. Among the genus Naja, the longest member arguably may be the forest cobra (Naja melanoleuca), which can reportedly grow up to 3 m. In the case of the Indian cobra (Naja naja), the majority of adult specimens range from 1 to 1.5 m in length. Some specimens, particularly those from Sri Lanka, may grow to lengths of 2.1 to 2.2 m, but this is relatively uncommon.

Blind snakes (Leptotyphlopidae)

 * The largest blind snake Giant blind snake (Rena maxima) is a female with a snout-to-vent length (SVL) of 33 cm plus a tail 1.8 cm long.

Lamprophids (Lamprophiidae)

 * The largest lamprophids Cape file snake (Heterolepsis capensis) is a medium to large snake. With an average total length (including tail) of about 120 cm, specimens of 165 cm total length have been recorded. It has a very flat head, and its body is strikingly triangular in cross-section.

Vipers (Viperidae)

 * The Gaboon viper (Bitis gabonica), a very bulky species with a maximum length of around 2 m, is typically the heaviest non-constrictor snake and the biggest member of the viper family, with unverified specimens reported to as much as 20 kg. The wild verified largest specimen of 1.8 m total length, caught in 1973, was found to have weighed 11.3 kg with an empty stomach. And therefore, the heaviest venomous snake and also the largest species of viper in present usually is an eastern diamondback rattlesnake (Crotalus adamanteus) with a maximum reliable mass in 15.4 kg and maximum length of 2.4 m. While not quite as heavy, another member of the viper family is longer still, the South American bushmaster (Lachesis muta), with a maximum length of 3.65 m.
 * The rattlesnake genus Crotalus, which includes the aforementioned eastern diamondback rattlesnake and western diamondback rattlesnake (Crotalus atrox), reaches a maximum length of 2.13 m, and according to W. A. King one large specimen had a length of 2.26 m and a mass of 11 kg. The third largest rattlesnake is the Mexican west coast rattlesnake (Crotalus basiliscus), which reaches 2.04 m long and 7.7 kg mass, and one captive-raised male was weighed at 8.8 kg in 2020.

Remarkable individual specimens
Individual specimens considered among largest measured for their respective species include the following:
 * Burmese pythons:
 * Wild caught (non-native invasive) Burmese python (Python bivittatus) female♀ 5.7912 m (19 ft) 56.699 kg caught in the Big Cypress National Preserve in eastern Collier County, Florida by Jake Waleri and Stephen Gauta on July 10, 2023. Waleri and several friends caught the large snake. They brought it to the Conservancy of Southwest Florida to have it officially documented. New current world record longest Burmese Python recorded by official measurement July 12, 2023.
 * "Baby" a captive Burmese python (Python bivittatus) female♀ 5.74 m, 182.8 kg; "Baby" was kept at Serpent Safari in Gurnee, Illinois, until its death at almost 27 years old, euthanized due to deteriorating condition caused by a tumor in 2006. Several live measurements and post mortem measurement.
 * "Hexxie" a captive Burmese python (Python bivittatus) female♀ 5.48 m, 110 kg and still growing; "Hexxie" lives in a terraced house in Tewkesbury, Gloucestershire, England, with owner Marcus Hobbs.
 * Wild-caught non-native (invasive) Burmese python (Python bivittatus) female♀ 5.39 m, 98 kg and measured 64 cm in diameter; She was carrying 122 developing eggs. Caught by a team of biologists in Everglades, Florida, June 22, 2022.
 * Wild-caught non-native (invasive) Burmese python (Python bivittatus) male♂ 5.23 m, 94 kg and measured 66 cm in diameter; caught by Okeechobee Veterinary Hospital, Florida, July 31, 2009.
 * Wild-caught non-native (invasive) Burmese python (Python bivittatus) female♀ 5.72 m, 104 lb; caught in Miami-Dade County, Florida, October 2, 2020.
 * Wild-caught non-native (invasive) Burmese python (Python bivittatus) female♀ 5.68 m, 128 lb; caught in Miami-Dade County, Florida, May 11, 2012. Intact specimen measured post mortem by University of Florida.
 * Wild-caught non-native (invasive) Burmese python (Python bivittatus) female♀ 5.56 m, 133 lb; caught by University of Florida wildlife biologist in Miami-Dade County, Florida, July 9, 2015. Intact specimen measured post mortem by University of Florida.
 * Wild-caught non-native (invasive) Burmese python (Python bivittatus) female♀ 4.57 m, 144 lb; caught by Nicholas Banos and Leonardo Sanchez, Everglades, Florida, April 1, 2017.
 * Wild-caught non-native (invasive) Burmese python (Python bivittatus) female♀ 5.2 m, 140 lb; she was carrying 73 developing eggs. Caught by Big Cypress National Preserve, Florida, April 7, 2019.
 * Reticulated pythons:
 * "Medusa" a captive reticulated python (Malayopython reticulatus) female♀ 7.67 m 350 lb; "Medusa" is kept at the Edge of Hell haunted house attraction in Kansas City, Missouri, and was last officially measured in 2011.
 * "Samantha" a captive (originally wild-caught near Samarinda, Borneo, as an already very large adult) reticulated python (Malayopython reticulatus) female♀ 7.92 m, somewhat reliable in 2002
 * "Fluffy" a captive reticulated python (Malayopython reticulatus) female♀ 7.3 m 136 kg; "Fluffy" was last officially measured live on September 30, 2009, and died at the Columbus Zoo and Aquarium in Powell, Ohio, on October 26, 2010, due to an apparent tumor. She was 18 years old. 24 feet confirmed when measured at death.
 * "Colossus", a captive reticulated python (Maylayopython reticulatus) male♂, skeletal measurement 6.35 m 133.7 kg; "Colossus" was kept at the Highland Park Zoo in Pittsburgh, Pennsylvania, died in April 1963, and the body was deposited at the Carnegie Museum.
 * "Twinkie" a captive reticulated python (Malayopython reticulatus) female♀ 7 m 156 kg; "Twinkie" found sanctuary in the 2014 Guinness World Records book as the world’s largest albino python in captivity. She was a fixture at The Reptile Zoo in Fountain Valley, CA.
 * "Super Snake", a captive reticulated python (Malayopython reticulatus) 14-year-old female♀ 7 m, 115 kg; "Super Snake" is kept at the National Aquarium in Al Qana, Abu Dhabi, United Arab Emirates.
 * Wild-caught reticulated python (Malayopython reticulatus) Female♀ 7.5 m adjusted post-mortem measurement, unreliable, originally measured alive at 8 m unreliably, using an unknown method, 550 lb – estimated weight upon capture, unreliable; caught April 7, 2016, Paya Terubong district, Penang Island, Malaysia. Died April 10, 2016.
 * Wild-caught reticulated python (Malayopython reticulatus) unknown sex 7.8 m, unverified; Was killed on October 5, 2017, Pekanbaru, Indonesia.
 * Wild-caught reticulated python (Malayopython reticulatus) unknown sex 6 m, 80 kg; Probably, this is largest snake in Phuket in last decade. Caught by Ruamjai Rescue Foundation, December 18, 2014, Phuket, Thailand.
 * Australian scrub pythons:
 * "Maximus" a captive scrub python (Simalia kinghorni) male♂ 5.1 m, 25 kg, at the peak weighed about 27 kg, when he was last weighed and measured in 2008; "Maximus" is believed to be the largest Australian native snake in captivity. He is kept at the Currumbin Wildlife Sanctuary on the Gold Coast, Queensland.
 * Wild-caught scrub python (Simalia kinghorni) unknown sex 5 m, 28 kg; caught by Machans Beach in Cairns, Queensland, November 14, 2017.
 * Wild-caught scrub python (Simalia kinghorni) unknown sex 5.1 m, 27 kg; caught by Speewah in Mareeba, Queensland, unknown date.
 * Wild-caught scrub pythons (Simalia kinghorni) unknown sex Both of were more 5 m (Second caught as stated measuring 5.1 m long and 27 kg in weight); caught by Speewah in Mareeba, Queensland, October 24, 2016.
 * Wild-caught scrub python (Simalia kinghorni) unknown sex 5.2 m, 22 kg; caught by Speewah in Mareeba, Queensland, February 6, 2017.