How Big Do Hamsters Get? (Size & Growth Chart)

Hamsters are fun pets for adults as well as children. Their low-maintenance nature combined with their adorable appearance makes them easy to love. However, one important thing to know before adopting one of these little rodents into your house is how big they get. After all, you don’t want to end up with unexpected surprises!

Today, we’re going to take a closer look at the growth progress of the hamster. We’ll cover everything you need to know from then they’re a baby until they’re fully grown to give you the most complete overview possible. Of course, there are also differences between the hamster species, which also have to be covered. Let’s get started.


How big do Syrian hamsters get?

Massive Syrian hamster. Image source: Reddit

Syrian hamsters are the biggest of the hamster breeds. Fully grown, they’re about 6 to 8 inches in length and typically weigh between 150 and 200 grams (5.3-7 oz).

Of course, they’re much smaller when they’re born. A newborn Syrian hamster is typically only 2 to 3 grams. However, they do grow quite quickly. Here is a complete growth chart of the Syrian hamster from 3 weeks until 15 weeks.

AgeWeight range in grams
3 weeks30-45
5 weeks50-100
7 weeks83-140
9 weeks110-170
11 weeks120-200
13 weeks130-210
15 weeks135-225
Syrian hamster growth data sourced from Charles River

After about 15 weeks Syrian hamsters stop growing because that’s when they’re fully grown adults.

One interesting thing to note is that while female Golden hamsters are lighter when they’re younger, they’re actually heavier when they’re fully grown.

How big do dwarf hamsters get?

Dwarf hamsters are much smaller than their golden cousins. There are a few different dwarf hamster species, so to avoid generalizing too much we’re going to look at each of them individually.

How big do Roborovski hamsters get?

I, AndreasF, CC BY-SA 2.5, via Wikimedia Commons

Roborovskis are the smallest of the dwarf hamster species. They’re only 1.5 to 2 inches fully grown and weigh around 1 ounce (20 to 25 grams).

Unfortunately, there is no accurate data available that covers the growth of the Robo hamster from birth to adult. However, what is known is that a baby Robo is only 1 gram at birth, so they grow quite a bit into adulthood. Considering the fact that Robo’s reach adulthood in the span of only 2 months, they grow remarkably quickly.

How big do Winter White/Campbell hamsters get?

While I separated the dwarf hamster species to avoid generalizing too much, the Campbell and Winter White hamster are genetically very similar. In fact, they are so similar that they can even interbreed to create hybrids. As such, they’re quite similar in size.

A fully grown winter white hamster is typically between 3 and 4 inches long and weighs between 1 and 2 ounces. Campbell’s dwarf hamsters are typically between 2 and 4 inches long and weigh 1 to 2 ounces.

Similar to the Robo hamster, there are no growth charts available that map the growth of these dwarf hamsters from baby to adult.

How big do Chinese hamsters get?

People often lump Chinese hamsters in with the dwarf hamsters, but they’re actually not dwarf hamsters. Nevertheless, they are quite small at a length of only 4 to 5 inches (with their tail included) and weight of 30 to 45 grams fully grown.

As babies, Chinese hamsters weigh only 1.7 grams and they mature in the span of only 2 months.

Hamster breeds size comparison chart

To get a quick overview of the sizes of hamsters when they’re born and fully grown, take a look at this growth comparison chart.

SpeciesSize as baby (grams)Size fully grown (grams)Length
Syrian2-3 grams150-200 6 to 8 inches
Roborovski1 gram20-25 1.5 to 2 inches
Winter White2 grams30-50 3 to 4 inches
Campbell’s2 grams30-50 2 to 4 inches
Chinese 1.7 grams30-45 4 to 5 inches
This chart shows a quick overview of the size of the different pet hamster species

My hamster weighs too much

Hamsters in captivity have access to a lot more food than wild hamsters do. On top of that, our pet hamsters don’t really have to work for their food. The only thing they have to do is be their cute little selves and we take care of all their needs.

This lazy lifestyle might sound nice, but it can have the unwanted consequence of weight gain. Hamsters that are too fat can have a plethora of health issues that can drastically lower their lifespan which is why it’s important to prevent them from gaining too much weight.

To prevent your hamster from becoming overweight it’s important that you’re cautious of these two things:

Their diet. The most important thing to look at to prevent your hamster from gaining excess weight is its diet. Make sure that you feed them a diet that either closely mimics their natural diet or one that is optimized to contain all the nutrition they need.

Their daily food intake should consist primarily of seeds or commercial pellets, with a smaller part of their nutrition coming from fresh fruits and veggies. In addition, they can have the occasional piece of meat, fish, or nuts.

A mistake that people often make is giving their hamsters too many fatty or sugary snacks, which can lead to weight gain. Hamsters are very tiny animals, and as such, they do not need a whole lot of food. It’s easy to accidentally overfeed them.

Exercise. As previously mentioned, hamsters in the wild have to run, jump and fight for their food. Captive hamsters don’t have to do any of that. Because of that, we have to make sure that they get their exercise some other way. The best way for them to get enough exercise is to make sure that they have a wheel in their cage. In addition, you have to make sure that you get them out of their cage every now and then to play with them.

My hamster weighs too little

If your hamster weighs too little and you’re giving it enough food it’s a good idea to take it to the vet for a check-up. Unexplained weight loss can often be a symptom that something is wrong.

If the hamster you’re concerned about is fresh from the pet shop they might be underweight because they were underfed or because they had to compete with other hamsters for food. If that’s the case, try giving them foods that are high in protein to get them back up to a normal weight. Good foods to give them include hard-boiled eggs, a small piece of cooked chicken or turkey, or even insects. Hamsters are omnivores and animal protein is great for helping them gain weight.


Frequently asked questions

What is the biggest hamster?

Syrian hamsters are the biggest pet hamsters. They’re much bigger than the dwarf hamster breeds.

What is the smallest hamster?

The Roborovski Dwarf Hamster is the smallest pet hamster. They’re only 1.5 to 2 inches fully grown, which is about 4 times smaller than the Syrian hamster.


Final words

Hamsters come in a wide variety of weights and sizes. From the tiny Robo to the might Syrian, their weight and lengths are very different from one another. This overview of their sizes from birth until adulthood gives you an excellent overview of what to expect from each of the hamster species.

Jesse A.