King Cobra (Ophiophagus hannah): Facts, Size and Venom

Appearance

The king cobra is a long, fairly heavy-bodied snake with smooth scales, a rounded snout and large eyes with round pupils and a golden iris. Adults vary in color across the range: olive green, yellowish brown, brownish gray or almost black, usually with pale yellow or white crossbands or chevrons that are bold in some regions and faint or absent in others. The throat is cream or pale yellow.

On top of the head sits a pair of large scales called occipitals, a feature that separates the king cobra from the true cobras of the genus Naja. Its hood is narrower and longer than that of an Indian or monocled cobra, and it has no “spectacle” or “monocle” mark on the back. Our guide why do cobras spread their hoods? explains how the hood works.

Young king cobras look very different from adults. Hatchlings are glossy black with narrow white, yellow or buff bands that form chevrons pointing toward the head. These bold markings fade as the snake grows. Like all members of the family Elapidae, the king cobra has short, fixed fangs at the front of the upper jaw.

How big do king cobras get?

Most adults measure 3.2–4 m (10.4–13.1 ft). The longest reliably measured king cobra was about 5.85 m (19.2 ft), and snakes over 5 m (16.4 ft) are exceptional. That makes it clearly the longest venomous snake on Earth; Africa’s longest, the black mamba, usually reaches 2–3 m (6.6–9.8 ft).

Unusually for snakes, males grow larger than females. In a study of wild snakes captured in Kerala, India, males reached about 3.75 m (12.3 ft) and 10 kg (22 lb), while the largest females were about 2.75 m (9 ft) and 5 kg (11 lb). Typical adults weigh about 4–6 kg (9–13 lb), and the heaviest males can exceed 10 kg (22 lb).

For how it compares with pythons and anacondas, see our list of the largest snakes.

Habitat and range

The king cobra has one of the widest ranges of any Asian snake, although it is rarely seen. It occurs in India (the Western Ghats, Eastern Ghats, Himalayan foothills, the northeast, the Sundarbans and the Andaman Islands), southern Nepal, Bhutan and Bangladesh, and east through Myanmar, Thailand, Laos, Cambodia and Vietnam to southern China, including Hainan and Hong Kong. To the south it ranges through the Malay Peninsula and Singapore to Sumatra, Java, Borneo and the Philippines.

It is mainly a forest snake. It lives in lowland and hill evergreen forest, deciduous forest, bamboo thickets and mangrove swamps, usually not far from streams, from sea level up to about 2,000 m (6,600 ft). It also moves through tea, rubber and oil palm plantations and farmland next to forest, which brings it into contact with people.

King cobras are mostly active by day. They hunt on the ground but climb well and swim readily, and radio-tracked snakes in Thailand and India have been found to roam large home ranges of several square kilometers.

One species or four?

In 2024 a team of researchers published a genetic and anatomical study proposing that the king cobra is not one species but four. Under this proposal Ophiophagus hannah is restricted to the northern populations, from the Himalayan foothills and eastern India to Indochina and southern China. The others are the Western Ghats king cobra (O. kaalinga) of southwestern India, the Sunda king cobra (O. bungarus) of the Malay Peninsula and the Sunda Islands, and the Luzon king cobra (O. salvatana) of the northern Philippines.

The four lineages differ in genes and in features such as the number and shape of their pale crossbands. Not every authority has adopted the split yet, and the IUCN Red List still assesses the king cobra as a single species, so this article treats it as one species with four distinct regional forms.

What do king cobras eat?

The scientific name Ophiophagus means “snake-eater”, and other snakes make up most of the king cobra’s diet. Recorded prey includes Oriental rat snakes and other rat snakes, keelbacks, wolf snakes, banded kraits, Indian cobras, pit vipers and young reticulated pythons. Monitor lizards and other lizards are also eaten, and birds or rodents are taken only occasionally.

The king cobra hunts actively, following scent trails with its forked tongue, then bites and holds its prey until the venom takes effect before swallowing it whole, head first. Because snakes are long, thin and slow to digest, one meal can last a long time; after a large meal a king cobra may go weeks or even months without eating. It also eats smaller king cobras when it gets the chance. Read more in why do king cobras eat other snakes?

Venom

The king cobra’s venom is mainly neurotoxic: its chief toxins are three-finger toxins that block the signals between nerves and muscles, causing paralysis, along with enzymes that damage tissue. Drop for drop, it is less potent than the venom of many other elapids, such as the inland taipan or several sea snakes. What makes the king cobra formidable is the amount it can deliver, often several hundred milligrams of dried venom in a single bite.

Bites on people are uncommon, because king cobras live in forest and usually move away from people. A serious bite is nonetheless a life-threatening emergency: anyone bitten should seek emergency medical help immediately. Our article how venomous is a king cobra? covers venom yield and potency in more detail.

Behavior and the famous “growl”

King cobras are usually shy and avoid people. When cornered or provoked, a king cobra raises the front part of its body, often a meter (3.3 ft) or more off the ground in a large snake, spreads its hood, stares at the threat and hisses. It can glide forward while reared up, so it can strike farther than people expect.

Its hiss is unusually deep. Most snake hisses cover a broad band of roughly 3,000–13,000 Hz, but a king cobra’s sound lies below 2,500 Hz, with a dominant frequency near 600 Hz, closer to the pitch of a human voice. Small pouches off the windpipe, called tracheal diverticula, act as resonating chambers and produce this “growl”.

Males fight during the breeding season. Rivals rear up, wrestle and try to push each other’s heads down, but they do not normally bite each other in these contests.

Reproduction and life cycle

Mating usually takes place from about January to April, depending on the region. A few weeks later the female does something no other snake is known to do: she builds a nest. Using loops of her body, she rakes dead leaves and other litter into a mound, often at the base of a tree, with a chamber inside for the eggs. Nests can be up to about 55 cm (22 in) high and 140 cm (55 in) across.

Clutches range from 7 to 43 eggs. The female stays at or near the nest for days to weeks and defends it vigorously, which is when king cobras are most likely to stand their ground. Incubation lasts about 66–105 days, and most females leave before the eggs hatch. The 37.5–58.5 cm (15–23 in) hatchlings are fully venomous from birth and fend for themselves at once. Our article do king cobras build nests? explains the nest in detail.

The king cobra’s lifespan in the wild is poorly known and is often estimated at about 20 years. Captive king cobras have lived about 17 years.

Predators, threats and conservation status

Adult king cobras have few natural predators, although mongooses and large birds of prey may attack them, and young snakes are eaten by birds and other snakes. The real threats come from people. Forest is being cleared for farms, plantations and settlements across Southeast Asia and India, and king cobras are often killed on sight.

They are also caught for their skins, for meat and for use in traditional medicine, and some are taken for the live-animal trade or for snake shows. Roads cut through forest add to the toll.

The IUCN Red List classes the king cobra as Vulnerable, with a decreasing population trend. It is listed in Appendix II of CITES, which regulates international trade, and it is legally protected in several range countries, including India, China and Vietnam.

If the 2024 split is widely accepted, some of the new species, especially those with small ranges such as the Luzon king cobra, may need their own assessments and could prove to be more threatened than the complex as a whole. Long-term radio-tracking projects in Thailand and India are teaching researchers how king cobras use farmland and forest, information that helps reduce conflict with people.

Myths and facts

Myth: King cobras chase people. King cobras normally retreat. Defensive behavior is mostly seen when a snake is cornered, handled or guarding a nest.

Myth: Snake charmers’ cobras dance to the music. Snakes have no external ears and hear airborne sound poorly. A charmed cobra sways to follow the movement of the flute and the charmer, which it treats as a threat. See can snakes hear?

Myth: A cobra’s mate takes revenge. A widespread South Asian legend says that a killed cobra’s partner hunts down the killer. There is no evidence for this; snakes do not form lasting pairs or seek revenge.

Relationship with people

The king cobra is the national reptile of India and holds an important place in the folklore and religious traditions of India, Bangladesh, Sri Lanka and Myanmar. It is one of the most recognizable snakes in the world and a star attraction in zoos, yet it is rarely encountered in the wild, and people who live alongside it in places such as the Western Ghats increasingly see it as part of the forest rather than a monster to be killed.