30 kg66.1 lb
An adult emperor penguin weighs about 30 kg (66 lb), but the real figure depends on the season. Adults range from about 22 to 45 kg (49 to 99 lb): males start the winter breeding season near 38 kg (84 lb) and drop to about 23 kg (51 lb) after roughly four months without food.
| Heaviest adultsTop of the normal range, according to Guinness World Records | 45 kg99.2 lb |
|---|---|
| Male at the start of the breeding fastAverage of males weighed by French researchers | 38.2 kg84.2 lb |
| Typical adultA middle figure for a bird whose weight changes all year | 30 kg66.1 lb |
| Male at the end of the breeding fastAbout 40% lighter after roughly 115 days | 22.8 kg50.2 lb |
| Newly hatched chickAbout 11 oz | 315 g11.1 oz |
Emperor penguins are the tallest and heaviest of the 18 living penguin species. Most sources give adults a weight of about 22 to 45 kg (49 to 99 lb) and a height of 1.1 to 1.3 m (3 ft 7 in to 4 ft 3 in). Males are heavier than females.
No single number fits, because an emperor penguin gains and loses a large share of its body weight every year. The Australian Antarctic Division says adults can weigh up to 40 kg at the start of the breeding season, and WWF puts a typical bird at around 40 kg before noting that this changes through the year. Our figure of 30 kg (66 lb) sits in the middle: well below a bird fattened up for winter, well above one at the end of its fast.
Emperor penguins breed on the sea ice in the Antarctic winter, often far from open water. The male stays at the colony through about six weeks of courtship and then about two months of balancing the single egg on his feet, eating nothing the whole time. All in all, that is a fast of about 115 days.
Studies by René Groscolas and colleagues from Strasbourg found that males fell from an average of 38.2 kg (84 lb) to 22.75 kg (50 lb) over the fast, a loss of 40.5%. New Zealand Birds Online says the loss can reach 45% of body weight. Females fast for a shorter time and lose about 22% of their starting weight.
To build those reserves, adults eat more than usual before breeding and moulting. The Australian Antarctic Division puts normal intake at 2 to 3 kg (4.4 to 6.6 lb) of fish, krill and squid a day, rising to as much as 6 kg (13 lb) a day when they fatten up. Satellite tracking by Gerald Kooyman’s team suggests that some males at colonies close to open water may slip away to feed during the winter, shortening their fast to 70 or 90 days.
The female lays one egg weighing about 460 to 470 g (16 to 17 oz), only about 2.3% of her own body weight, and the male incubates it for about 65 days. The chick weighs around 315 g (11 oz) when it hatches.
Both parents then shuttle food from the sea. The Australian Antarctic Division estimates that a chick needs about 42 kg (93 lb) of food from each parent before it can fend for itself. It leaves the colony at about 141 days old, when it weighs roughly half as much as an adult.
The emperor penguin is the heaviest penguin alive today, but fossils from New Zealand show that much bigger ones once lived. Guinness World Records lists Kumimanu fordycei, described in the Journal of Paleontology in February 2023, as the heaviest penguin species ever. By comparing the size and density of its bones with those of living penguins, researchers estimated it at 154 kg (340 lb), about three times an emperor penguin’s weight.
It lived 55.5 to 59.5 million years ago. The previous record holder, the colossus penguin from about 37 million years ago, was estimated at about 115 kg (254 lb) and up to 2 m (6 ft 6 in) tall.
An adult weighs about 66 lb (30 kg) on average, within a range of roughly 49 to 99 lb. A male can weigh about 84 lb before the winter breeding fast and about 50 lb after it.
Adults are about 1.1 to 1.3 m (3 ft 7 in to 4 ft 3 in) tall, which makes them the tallest living penguins. WWF compares a 120 cm emperor penguin to a six-year-old child.
During a fast of about 115 days through courtship and incubation, males lose around 40% of their body weight, typically falling from about 38 kg to 23 kg (84 to 50 lb). Some lose up to 45%.
A chick weighs about 315 g (11 oz) when it hatches from an egg of about 460 g. It leaves the colony at roughly 141 days old, at about half an adult’s weight.
The emperor penguin is the heaviest living species. The heaviest known species of all time is Kumimanu fordycei, a fossil penguin from New Zealand estimated at 154 kg (340 lb).
Last checked October 2, 2026.
