Ever seen a polar bear in person? If you have, you know they aren’t just "big." They are architectural marvels of fat and muscle. But when we talk about how much do polar bears weight, the answer is never just a single number on a scale. It’s a moving target.
An adult male can weigh as much as a small car. Or he might weigh half that if he’s had a rough summer. It's honestly wild how much their bodies fluctuate. We're talking about animals that can gain or lose 100 pounds in a matter of weeks depending on whether the seals are biting.
The Big Divide: Males vs. Females
In the world of Ursus maritimus, gender is the biggest factor in size. There is a massive gap here.
Adult males, often called "boars," are the true giants. Most of them tip the scales between 800 and 1,300 pounds (about 360 to 590 kg). Some absolute units can push past 1,500 pounds if they’ve been feasting on ringed seals all spring. They keep growing until they are about 8 or 10 years old.
Females are a different story.
A typical adult female weighs roughly 330 to 650 pounds (150 to 295 kg). They are basically half the size of the males. But there’s a catch. When a female is pregnant, she has to pack on an incredible amount of "baby weight" to survive months in a den without eating. A pregnant polar bear can actually double her body weight, sometimes hitting 1,100 pounds before she retreats into the snow.
Why the difference?
Scientists like the late Dr. Ian Stirling, a legend in polar bear research, noted that this "sexual dimorphism" is all about roles. Males need the bulk to fight other males for mating rights. Females just need enough fat to nurse their cubs through the winter.
From One Pound to a Ton: The Growth Journey
It’s hard to believe, but these 1,000-pound predators start out looking like a stick of butter.
📖 Related: 101 Questions to Ask Before Getting Engaged: Why Most Couples Skip the Hard Stuff
When a polar bear cub is born in December or January, it weighs about 1 to 1.5 pounds. That's it. You could hold one in the palm of your hand. They are blind, toothless, and covered in hair so fine they look naked.
But then comes the milk.
Polar bear milk is about 31% fat. For comparison, cow's milk is around 4%. This "Arctic milkshake" is so calorie-dense that the cubs grow at an explosive rate. By the time they leave the den in March or April, they’ve jumped to 22–33 pounds.
By their first birthday, they might weigh 200 pounds. By age two, a male cub is often already the size of his mother. It’s a frantic race to get big enough to survive the harsh Arctic winters.
The Record Breakers: The 2,210-Pound Legend
If you want to know the upper limit of how much do polar bears weight, we have to look back to 1960.
📖 Related: Why the Tip of the Beast's Tongue is More Than Just a Myth
In Kotzebue Sound, Alaska, a male polar bear was recorded that defied everything we thought we knew about bear size. This bear weighed a staggering 2,210 pounds (1,002 kg). When he stood on his hind legs, he was nearly 12 feet tall.
To put that in perspective, that bear weighed as much as 11 average-sized men combined. While most bears today don't reach those mythical proportions—largely due to shorter hunting seasons—it shows what the species is capable of when the environment is perfect.
The Seasonality of Fat
Weight isn't static in the Arctic. It’s a cycle of "feast or famine."
Polar bears get about two-thirds of their yearly energy in late spring and early summer. This is when seal pups are born and are easy to catch on the ice. During this time, a bear might gain several pounds of fat every single day.
Then comes the "walking hibernation."
When the sea ice melts in the summer, bears in places like Western Hudson Bay are forced onto land. There are no seals on land. They might forage for berries or seaweed, but it doesn't do much. A study from Washington State University recently showed that bears on land lose about 2.2 pounds (1 kg) per day.
The Climate Factor
This is why sea ice is so critical. If the ice melts too early, the bears don't have enough time to reach their "target weight." Every week lost on the ice means a bear starts the summer fasting period thinner and weaker. Thinner bears have fewer cubs, and those cubs are less likely to survive their first year.
Quick Reference: Weight by the Numbers
Instead of a boring chart, let's look at it through the lens of what these weights actually mean in the wild:
🔗 Read more: German Shepherd Attack Dog: The Truth About Why They Bite and How to Handle Them
- The Newborn (1 lb): Totally helpless. Smaller than a guinea pig.
- The Den Emerger (25 lbs): About the size of a Beagle. Ready to see the sun for the first time.
- The Average Female (450 lbs): Roughly the weight of a high-end refrigerator.
- The Heavyweight Male (1,200 lbs): As heavy as a grand piano.
- The Record Holder (2,210 lbs): Heavier than a 2026 subcompact electric car.
Actionable Insights for Wildlife Enthusiasts
If you're tracking polar bear health or planning a trip to see them in places like Churchill, Manitoba, keep these details in mind:
- Check the Season: If you visit in October, the bears will look their thinnest. They’ve been fasting all summer. If you want to see them at their "chunkiest," you’d have to see them on the ice in June—which is much harder to do!
- Look at the Neck: Experts often judge a bear’s weight by its neck and "trousers" (the fur on the back of their legs). If the neck is wider than the head, that’s a healthy, fat bear.
- Support Ice Conservation: Since weight is directly tied to hunting time on the ice, supporting organizations like Polar Bears International helps fund the research needed to understand how changing ice patterns are affecting these weights.
- Don't Compare to Grizzly Bears: Remember, polar bears are "marine mammals." They are built differently. They have a four-inch layer of blubber that grizzlies don't have, which is why they often look "smoother" and heavier than their brown cousins.
The weight of a polar bear is the ultimate indicator of the Arctic’s health. When the bears are heavy, the ecosystem is working. When they start to thin out, it’s a signal that the balance is shifting.