The blue whale is a baleen whale, a kind of whale that feeds by straining small animals out of seawater. As of 2026, it is the largest animal known to have lived on Earth. A fully grown blue whale is about 20–30 meters (65–100 feet) long. The explorer shows one 30 meters (98 feet) long, a large adult at the top of that range.

Size

A whale's size is given as its body length. Guinness World Records puts a fully grown blue whale at about 20–30 meters long, weighing about 160 tonnes (a tonne, or metric ton, is 1,000 kilograms). As in many baleen whales, females are generally larger than males.

Size also depends on where a whale lives. NOAA Fisheries, a U.S. government agency, says blue whales in the North Atlantic and North Pacific grow up to about 27 meters (90 feet). Those in the Antarctic reach about 33.5 meters (110 feet). Pygmy blue whales, a smaller subspecies (a distinct group within the species) that feeds off southern Australia, grow to about 25 meters (82 feet).

As of 2026, the longest blue whale on record was a female brought to the whaling station at Grytviken, South Georgia, in 1909. She was recorded as 107 Norwegian feet, about 33.6 meters (110 feet). The heaviest on record, a 27.6-meter (90-foot) female caught in the Southern Ocean on March 20, 1947, weighed 190 tonnes.

Size comparisons

A 30-meter blue whale is about as long as 18 people 1.7 meters (5 feet 7 inches) tall, lying head to toe.
A Boeing 747-8 airliner, 76.25 meters (250 feet) long, is about as long as two and a half such whales.
It would take nearly four 30-meter whales, nose to tail, to cover the length of an American football field, 110 meters (120 yards) with its end zones.
The heaviest blue whale on record weighed nearly three times as much as the giant dinosaur Patagotitan, whose weight its describers estimated at 69 tonnes.

How a blue whale feeds

Blue whales feed almost entirely on krill, small shrimp-like animals. Plates of baleen hang from the roof of the mouth and work like a sieve. A feeding whale swims into a swarm of krill with its mouth open, and pleats in its throat stretch to hold the water. It then pushes the water out through the baleen with its tongue, trapping the krill inside.

One mouthful can hold up to 50 tonnes of water and krill, according to the Australian Antarctic Program. Blue whales generally feed in cold polar waters in summer. As winter comes, many of them migrate toward the equator.

Calves and whaling

A newborn calf is 6–8 meters (20–26 feet) long and weighs about 2.5–3 tonnes. Toward the end of nursing, a calf can gain 100 kilograms (220 pounds) a day. Blue whales are thought to live about 80–90 years.

Whaling killed blue whales in huge numbers in the twentieth century: at South Georgia alone, 30,000 were killed in the 1930–31 season. The International Whaling Commission banned their commercial hunting in 1964. The Australian Antarctic Program estimates that Southern Hemisphere blue whales, not counting pygmy blue whales, fell from about 225,000 before whaling to probably fewer than 2,000. The species is listed as endangered, but as of 2026 NOAA reports that populations are increasing worldwide.

Sources

Blue Whale. NOAA Fisheries, 2026.
Blue whale. Australian Antarctic Program, 2024.
Largest mammal. Guinness World Records.
A new giant titanosaur sheds light on body mass evolution among sauropod dinosaurs. Carballido et al., Proceedings of the Royal Society B, 2017.
747-8/747-8F Airplane Characteristics for Airport Planning. Boeing, 2026.
2026 NFL Rulebook. National Football League, 2026.

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