Average Pet Rat Size (With Images)

A pet rat’s size can vary, this is not up to the breed though. Just like people, they just come in different sizes. I’ve seen rather small or average size pet rats, but also very big ones!

On average, the size of an adult pet rat is 9 to 10 inches ( 22.86 to 25.4 cm), plus an average tail length of 8 inches (20.32 cm). Male pet rats tend to be bigger than the average female.

Mostly, their size will vary according to their background or their sex. For example, wild rats and domestic rats can have different sizes. Female pet rats tend to be smaller than male rats as well. But let’s dive into this a bit more!

How Big Can A Pet Rat Be?

There’s no such thing as breeds with pet rats, but there are different species, and that can change the maximum size of a pet rat! The brown rat is the most common domesticated species, but there’s also the albino ones, hairless and even tailless.

There are quite a few injuries that a pet rat can have on their tail, as you can read here. Which I guess wouldn’t happen in a tailless rat!

I, for one, think it’s very weird to see a rat with no tail. It is a very important part of their body, responsible for their balance. They seem to have no problems whatsoever and this species has been bred for quite some years now.

If a small pet rat is something you desire, then this could be a solution.

A pet rat can grow up to 20 inches, from nose to tail. Their body can be around 9 to 10 inches and their tails up to 7 or 8 inches.

How Big can a pet rat be - here's the average size of a pet rat, they don't vary much from what you can see in the image.

In some, quite rare cases, pet rats can be bigger. I swear I had a friend who owned a pet rat that was the size of half of their arm! But again, this is quite rare to happen. I never had pet rats over the average size.

They are prey animals, so their body is designed to pass through small spaces, rather quickly. For this reason, their body won’t be too big. They can also compress their body to pass through very small spaces.

This is always important to know because most cages that are suitable for rats will have the bars too far apart from each other and your pet rat will be able to pass through them very easily. What we usually do is reinforce the bars with some wired panels, like these cube wired shelves!

They are very easy to set up and there’s no need for extra tools. Plus this way your pet rat won’t be able to escape the cage when you go to sleep!

How Big Can A Dumbo Rat Be?

Dumbo rats don’t stray too much from the average size.

The name itself might easily indicate what is their distinctive quality. They get this name from a recessive gene called, the dumbo gene. This happens when an animal gets two copies of this same gene from its parents.

The differences between a dumbo rat and the usual pet rat are that their ears are bigger. They’re very large and circular and their position goes lower in their heads. They appear sticking out in the sides, behind their cheeks.

For this reason, we call the more “regular” pet rats top-eared. To easily distinguish them from dumbo.

But, they’re exactly the same species. They’re both brown rats just with different qualities. For this reason, dumbo rats have the same average size as their top-eared friends!

A dumbo rat can go up to 20 inches as well, from nose to tail. Sometimes smaller, sometimes bigger. And like any other pet rat, females tend to be slightly smaller than the males.

Pet Rat Size During Their Life

A newborn pet rat will weight about 6 to 8 grams. This is how much a small coin can weight! They’re born with no fur, only a little bit of whiskers and their eyelids are sealed. They almost don’t even look like pet rats!

When they’re born, a pet rat is very, very small. About 1 to 2 inches! But this will quickly change. About a week after they’re born, their size won’t differ much, but you’ll notice a bit of fuzz starting to cover their skin.

With 15 days of age, a pet rat will already fill your hand considerably and their fur will cover their body fully, their eyes are fully open now and they can see much cleary. This means they’re also more active and will start to behave a bit more like a grown rat, only more energetic and curious!

When these adorable pet rats are born, they are very tiny! About 1 to 2 inches to be exact. But they grow quickly.

Pet rats mature very quickly! At about 5 weeks they’re already fertile and males and females should be in different cages from then on, to avoid pregnancies.

Finally, at 6 months, a pet rat becomes a full adult. At this point, they would hit their maximum size, of about 18 to 20 inches, tail included, as we mentioned before!

Male Rats vs Female Rats Size

Most of the times, male rats are bulkier and bigger, while female pet rats tend to be thinner and smaller.

The difference in size isn’t overwhelming though. Usually, you see their differences because males end up being much bulkier than the females.

The preference between males or females comes more from their personalities though. For example, male pet rats are more relaxed and like to cuddle…a lot! We can eve say that they are quite lazy.

If you’re looking for a calm pet, that prefers to cuddle next to you, a male rat would probably be a good option.

On the other hand, females are much more energetic. This makes them perfect to learn tricks! They are smaller, but definitely much more active than the males. Females love to roam about and teaching them tricks is the best way to keep them happy and active.

So, if you want to spend lots of time playing with your pet rats, then females would be perfect!

As for the smell, male rats have a stronger and muskier odor, but nothing too strong, like ferrets. And if you do a daily cleanup of the cage, you won’t even notice. We clean their litter every day and if it’s too dirty, change the litter once or twice a week.

This way it won’t be smelly and your pet rat will feel more comfortable as well. They’re very clean and even if their litter becomes too dirty, they’ll start doing their necessities somewhere else!

Smallest Pet Rat Breed

As I said, pet rats have no specific breed. There are just different varieties of them.

Small characteristics that distinguish them from each other. Some have bigger ears, some are hairless, albino, tailless and then they can have different colors and patterns among them.

In short, there is no smallest pet rat breed. Some pet rats will be smaller than others, but won’t go much further away from their average size.

If you’re looking for a smaller pet, then maybe a smaller rodent fits better for you.

Hamsters are much smaller than pet rats, even Syrian hamsters and they can also make great companions!

Related Questions

Why are rats tails so Long? For balance. The tails are a very important part of their body because it will help them scale, jump and even swim. It is because of their tails that they can so easily walk through wires, for example!

How much space does a pet rat need? Generally speaking, each rat, should have at least 2 cubic feet of space. A big cage, like one for ferrets, is the most appropriate space for them.

Pet rats don’t differ in size very much, unlike other animals like dogs and cats!

Their size will vary according to the stage of their (short) lives they are at and mostly on their sex. In general, females will be smaller and thinner than males.

But that’s mostly it!

Now that you have all this information, go get a pet rat!

Or if you already have pet rats, go snuggle up with them.

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Average Pet Rat Size With Images! Learn how big do pet rats get, and how tiny they are when they are born!

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