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How Big Can a Hamster Get? Vet Approved Average Weight & Growth Chart

Brooke Bundy

By Brooke Bundy

Close-up face of Winter White Russian Dwarf Hamster on girl hands

Vet approved

Dr. Chyrle Bonk Photo

Reviewed & Fact-Checked By

Dr. Chyrle Bonk

DVM (Veterinarian)

The information is current and up-to-date in accordance with the latest veterinarian research.

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Getting a hamster is the way to go if you want a small pet. Depending on the breed, hamsters grow to be anywhere from 2 to 9 inches long and only weigh up to 4-5 ounces even as an adult. They are ideal pets for first time pet owners or people who don’t have a lot of space. Be sure to do your research to know what hamster breed is right for you.


All About Hamsters

Nimble and nocturnal, hamsters spend their days sleeping and their nights turning circles on their wheels. These fascinating little creatures are fairly easy and inexpensive to maintain. The startup investment of buying the cage and accessories is the most financially involved part of caring for a hamster. In addition to daily food and water, hamsters need fresh litter and their bedding changed at least once a week. You may opt to always keep them in their enclosure or allow them to roll around the house in a hamster ball as long as there are no predators around, such as dogs or cats.

Hamster Size and Growth Chart

hand supporting the hamster to stand on its hind legs
Image Credit: Elena Vechkanova, Shutterstock

Although all hamsters are considered to be small pets, their length ranges considerably depending on the breed. Syrian hamsters are the largest breed of pet hamsters, weighing a whopping 5 ounces and growing up to 9 inches long. In comparison, most hamsters only weigh between 1 and 2 ounces. The three dwarf breeds are the smallest, with the Roborovski Dwarf Hamster being the smallest of all. Roborvoski Dwarf Hamsters typically weigh less than an ounce and measure between 2 and 4 inches when fully grown.

Here’s a chart that lists the five most popular hamster breeds with their expected weight and length:

Breed Weight Range Length Range
Syrian 3-5 ounces 5 to 7 inches
Chinese 1.1 to 1.6 ounces 3.2 to 5 inches
Roborovski Dwarf Hamster 0.7 to 1 ounce 2 to 3 inches
Winter White Dwarf Hamster 0.7 to 1.6 ounces 2.7 to 3.5 inches
Campbell’s Russian Dwarf Hamster 1.5 to 2 ounces 2 to 4 inches

When Does a Hamster Stop Growing?

Hamsters have a very short lifespan when compared to other pets such as cats and dogs. Most hamsters only live for a couple of years, though some may live up to 4 years depending on the breed. Because of their short lives, they grow up very quickly. A hamster is considered full-grown by 3 months old, which is also around the time most breeds will reach sexual maturity. Some breeds, however, may be capable of mating as young as 4 weeks old.


Factors Affecting the Size of a Hamster

Breed is the largest predictor of size. Although there are technically 24 hamster breeds in the world, only five are typically kept as pets. These five breeds have been bred so much that their physical characteristics are relatively easy to predict.

As with all animal species, however, individual genetics and environmental factors do play a role in determining a hamster’s actual size. There’s always a runt of the litter, and weaker animals tend to stay small since their siblings are able to push them out of the way when it’s time to eat.

two hamsters inside cage
Image Credit: HelloRF Zcool, Shutterstock

Ideal Diet for Maintaining a Healthy Weight

Of course, on the other side of the extreme, you could end up with an obese hamster if they receive too much food. Feeding your hamster the correct portions of a commercial pellet diet, supplemented with fresh fruits and vegetables, can help them stay on track for a healthy weight. Hamsters don’t eat much, typically only requiring between 1/8 and 1/3 cup of food each day. Don’t worry if you miss seeing them eat. Since they’re nocturnal, they’ll usually take their meals while you’re asleep.

How to Measure Your Hamster

If you’re curious how much your hamster weighs, place them on a kitchen scale to weigh them. You might want to cover the kitchen scale with a paper towel and thoroughly sanitize the surface afterwards to avoid the potential spread of germs to your food. To measure their length, stretch a soft tape from their nose to the tip of their tail, or have them stand on a piece of graph paper as you count the squares.

Keeping up with your hamster’s size can give you a good indication of their overall health. If they’re under 3 months, they should still be growing, so gaining length and extra weight is a good thing. If they’re putting on weight as an adult, however, you may want to consult your vet to see if you need to switch up their diet to prevent obesity.


Is a Hamster the Right Pet for You?

girl holding roborovski dwarf hamster
Image Credit: JulieK2, Shutterstock

Hamsters are fairly easy pets, but they aren’t for everyone. While they’re frequently bought as pets for children, you should carefully consider whether they’re the right pet for your individual household. For example, since they have sensitive ears, hamsters become stressed when they hear excessively loud noises and may hide.

Unfortunately, it’s also easy to accidentally hurt a hamster because of their small size. For this reason, they aren’t a great idea for households with toddlers. On the emotional side of things, hamsters typically don’t live very long lives, so you may have some explaining to do if your child walks in the room and finds their hamster has suddenly died. For this reason, we suggest getting a hamster for a mature child who can be sensitive with small creatures but won’t be terribly traumatized if it passes away.

You’ll also need to consider whether you or other members in your household want a pet that they can hold. If you’re looking for a tiny snuggle buddy, opt for one of the larger breeds like the popular Syrian hamster. This hamster is one of the most sought-after breeds because they tend to be more friendly and are bigger, so holding them is less likely to accidentally hurt them. Dwarf breeds are not only extremely tiny and fragile, but also a little more prone to biting. These little guys are great if you mostly want to watch them from afar, but don’t make the most amiable childhood pets to hold.


If you’re wanting to welcome a small animal into your house, a hamster fits the description perfectly. Most hamsters only weigh around an ounce, but some may reach up to 5 ounces depending on breed. When determining whether a hamster is right for you, be sure to consider other aspects of their breed characteristics and temperament to make sure they’re a good match.

Featured Image Credit: sabza, Shutterstock

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