How Big Do Guinea Pigs Get? Your Complete Guide to Piggy Proportions

One of the more common questions we receive from our readers is ‘how big do guinea pigs get’? Seems like a pretty straightforward question with a simple answer, right? Well, it would be if there was such a thing as an average-sized guinea pig, but this isn’t the case.

If you want to find out how big guinea pigs get, which breeds are bigger than others and at what age cavies are considered full-grown, carry on reading. We’re looking at all things related to piggy proportions, big, small and everything in between.

How Big Do Guinea Pigs Get? A Guinea Pig Size Guide

Guinea pigs, like cats and dogs, vary in size. Generally speaking, male piggies tend to be larger than females, and some breeds are bigger than others. Other factors also play a role, including the order of birth, diet, overall health and of course, genetics.

Boys Weigh More Than Girl Guinea Pigs

Typically, male guinea pigs, or boars, weigh more than females or sows. An adult male cavy, on average, can weigh anywhere between 2 and 2.6 pounds (900 and 1,100 grams). 

The Rex is by far the biggest cavy breed, Measuring around 17 inches long when full grown he is 50% bigger than most other breeds. and double the size of an American Guinea Pig. Click To Tweet

A female, on the other hand, will weigh around 1.5 to 2 pounds or between 700 and 900 grams.

In terms of length, male and female guinea pigs do most of their growing by 8 weeks old, almost doubling in size. 

By around 16 weeks, they are considered fully grown, and measure between 8 and 10 inches or 20 to 25 centimetres.

As a responsible guinea pig owner, it’s important that you regularly check your cavy’s weight to make sure it isn’t under or overweight. 

Both factors can have long-term health implications for your cuddly pal. 

Check out this helpful guinea pig size chart!

Different Breeds Are Different Sizes

Shape-wise, guinea pigs tend to be somewhat cylindrical, although they are often described as fluffy potatoes! But when it comes to their sizes, like dogs and cats, it depends very much on the breed. 

And with as many as 50 breeds to choose from according to the British Cavy Council, you’re bound to find the perfect sized piggy for you.

Can you guess which cavy breeds are is the smallest? And how about the largest? Let’s take a look and see how well you know your guinea pigs.

How big do guinea pigs get

Which Guinea Pig Is The Biggest?

The Rex is by far the largest breed of all the guinea pigs out there, measuring in at a rather impressive 43 cm or 17 inches long as an adult. Keeping in mind that the average breed is between 10 and 12 inches, this means the Rex is almost one and a half times bigger than other guinea pig breeds.

Although this breed is not recognized by the American Cavy Breeders Association, it certainly is celebrated here in the UK with its own Specialist Breed Club.  All that’s left to say is “Hail King Rex”!

Take a look at this cutie courtesy of The Pet FAQ

Which Guinea Pig Is The Smallest?

When it comes to the smallest guinea pig breed, the popular American guinea pig and the fairly newer Texel breed come in 1st and 2nd. 

Both these breeds are noticeably smaller than others, with the American measuring around between 8 and 9 inches (20-22 cm) as an adult. 

The Texel, in comparison to other breeds, is also tiny and measures approximately 8 to 10 inches long (20-25 cm)  when fully grown.

The photo below is courtesy of Little Furry Pets

Other Sizes

But what about the breeds in between?  On average, all the other cavy breeds get to around 20 cm or 12 inches (30.48 cm). Of course, their weights may vary and other factors such as genetics, diet and overall health and play a role. 

Also, depending on how many pups are born in a litter, they may be bigger or smaller than the average guinea pig size.

Let’s take a look at the popular breeds that fall into this size category.

  • The Abyssinian
  • The Teddy
  • The Ridgeback
  • The Peruvian
  • The Himalayan
  • The Crested

How Big Are Baby Guinea Pigs?

A newborn pup is only around 8 to 10 cm (3-4 inches) long when born. And often it’s only the breeder lucky enough to see a baby guinea pig at its tiniest.

But we’ve got a treat for you! This YouTube clip shows a mummy guinea pig cleaning off her babies immediately after giving birth…

PSA! Don’t be alarmed, she isn’t eating the babies… only cleaning them!

So To Recap

  • On average, guinea pigs measure between 20 and 25 cm as adults and can weigh anywhere between 700 and 1100 grams.
  • Males tend to grow larger and weigh more than females.
  • At birth, guinea pigs are tiny but do most of their growth within the first 8 weeks of being born,
  • The largest breed currently is the cute and cuddly Rex Guinea Pig.
  • The smallest breeds are the American and the Texel.
  • Depending on where you live in the world, you have between 14 and over 50 breeds to choose from.

To Finish Off

Any guinea pig parent will tell you how gentle, affectionate and lovable cavies are, making them a hugely popular pet in households in the UK, and the rest of the world.

However, they need a lot of care and commitment to keep them happy, healthy and well, from their enclosure to the food they eat and the amount of exercise they get. They also should never be kept alone, as depression and loneliness are bad for their health.

If you want to know how to look after your piggies, responsibly, this article is incredibly helpful.

We Want To Hear From You

Obsessed with guinea pigs? We are too! Long-haired, short-haired, hairless, big, small or somewhere in between, we love finding out as much as there is to know about our cute and cuddly cavy companions. And it seems you are too!

What kind of guinea pig have you got? Perhaps it hasn’t been mentioned in this article, and you want to tell us all about it. 

Feel free to leave a comment below, or post all the pics you want of your cuddly companions… We would love to share them with our readers.


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