How big do guinea pigs get? Discover the average guinea pig weight and how much a full-size guinea pig should weigh in this guide to guinea pig size.
As with any animal, adult guinea pig size can vary based on a number of factors. These include birth order, age, species, gender, diet, lifestyle, overall health, and genetics.
This makes the question of guinea pig size quite interesting. We’ll explore all of these aspects in this guinea pig size guide.
How Big Do Guinea Pigs Get?
So, how big do guinea pigs get? There is no single or simple answer to this question, but there are helpful guidelines.
A guinea pig’s size consists of its length, width, height, and weight. Most commonly, however, only length and weight are noted when measuring guinea pig size.
Let’s begin our look at guinea pig size by looking at average guinea pig weight.
Guinea Pig Weight
There is a significant difference between the average guinea pig weight for males and that for females.
A female adult guinea pig generally weighs between 1.5 and 2 pounds (700-900g). Whereas a male adult guinea pig generally weighs between 2 and 2.6 pounds (900-1,100g).
With numbers that small, it might not seem like a big difference. However, it means that a male full-size guinea pig generally weighs about one-third more than a female.
So, if you’re wondering how much should a guinea pig weigh, part of the answer is the weight range.
The vast majority of guinea pigs weigh somewhere between 1.5 and 2.6 pounds (700-1,100g). Of course, there will always be petite or large exceptions.
Full-Size Guinea Pig
So, how big do guinea pigs get?
As with hamsters, dogs, cats, and other popular household pets, there are several breeds of guinea pig that are kept as pets today. The American Cavy Breeders Association (ACBA) recognizes 13 guinea pig breeds, but there are many more breeds that they don’t recognize.
Some are quite large breeds, while others are much more petite. So, a guinea pig’s breed plays a significant role in its weight and length.
Unlike other animals in the rodent family, most guinea pigs do not have a visible tail that can count towards its overall length. Which is actually good, since this can be confusing when the tail length represents half of a rodent’s overall length!
For guinea pigs that do have visible tails, their tails are usually only between 1-1.5 inches (2.5-3.8 cm). They are often hidden from sight by the guinea pig’s fluffy fur coat.
The average guinea pig size in length ranges from 8 to 10 inches (20-30 cm).
Now that we know how big the average guinea pig is, let’s look at some exceptions.
Biggest Guinea Pig Breed
The award for the biggest guinea pig breed goes to the Rex guinea pig, which can grow up to 17 inches (43 cm) at maturity!
To date, no other modern guinea pig breed even comes close to the Rex guinea pig’s incredible adult length!
This one’s a gentle “giant” though as it’s also known as a low-maintenance lap pig that appreciates affection.
Large Guinea Pig Breeds
If you’re curious about how big do guinea pigs get, you’ll be intrigued to know that the larger guinea pig breeds grow across a length range of about 4 inches.
The larger pigs in each breed range from 10 to 12 inches (25-30 cm).
Here are some common and popular large guinea pig breeds:
- Himalayan: up to 12 inches (20 cm)
- Ridgeback: up to 12 inches (20 cm)
- Teddy: up to 12 inches (20 cm)
- Abyssinian: up to 12 inches (20 cm)
- Sheba: up to 12 inches (20 cm)
- Texel: up to 12 inches (20 cm)
- Cornet: up to 12 inches (20 cm)
- Peruvian: up to 12 inches (20 cm)
- Lunkarya: up to 12 inches (20 cm).
Abyssinian Guinea Pig Size
One of the most popular and unique pet guinea pig breeds is the Abyssinian.
These wonderful piggies have a stunning coat marked by cowlicks (“rosettes”) that create swirls of fur all over their body.
They also have lovely bands of color in their fur that can range from pure ivory to deep grey.
An Abyssinian full-size guinea pig can range from 8 to 12 inches (20-30 cm) depending on gender, birth order, litter size, diet, and overall health.
American Guinea Pig Size
The American guinea pig is one of the smaller breeds on the guinea pig size chart.
American guinea pigs tend to stay at the shorter end of the spectrum lengthwise, with adults only reaching about 8 to 9 inches (20-22 cm) at maturity.
How Big Are Baby Guinea Pigs?
If you think adult guinea pigs are cute, you should see them when they are babies!
Baby guinea pigs don’t stay babies for very long, however, so usually only breeders get to see these teensy versions of the adult pets we all love.
If you are wondering how big baby guinea pigs are, well, an infant guinea pig may be only 3 to 4 inches (8-10 cm) long at birth!
Weight-wise, a baby piggie will weigh between 2 and 4.5 ounces (60-130g) depending on birth order and litter size. The average birth weight is 2.8 ounces (80 g).
The larger the litter, the smaller the baby guinea pigs will be. Litters can range from one to eight babies, with the average litter being three.
Infant guinea pigs grow very fast. In just eight weeks, they will double in size and weight. In another eight weeks, they will nearly double in size and weight yet again.
By the time a baby guinea pig is just over a year old, it will be at its full adult length and weight.
How Big Do Female Guinea Pigs Get?
It is generally possible to tell whether a guinea pig is a male or a female by the time it reaches the age of three weeks.
The most common way is to palpate the abdominal area, but size can sometimes also be an indicator of gender. Males are generally 25-30% larger than females in both weight and length.
Most female guinea pigs will typically top out on the smaller end of the size range for their breed at between 8-10 inches (20-25 cm).
How Big Do Male Guinea Pigs Get?
Males are almost always larger than female guinea pigs of the same breed. They are the ones who are most likely to grow to the breed’s maximum length.
For instance, if you bring home an Abyssinian, you know that Abyssinian guinea pig size ranges from 8 to 12 inches (20-40 cm).
A male Abyssinian guinea pig is far more likely to grow to the full 12 inches than a female.
Biggest Guinea Pig Ever
If you can imagine a guinea pig that weighed 1,543 pounds (700 kg) and stood 1.4 yards (1.3 meters) tall, you are imagining Phoberomys pattersoni, the biggest guinea pig ever, which lived 8 million years ago in what is now northern Venezuela.
Phoberomys is officially the world’s biggest guinea pig, although scientists are still piecing together how it evolved into today’s pint-sized relatives.
Unlike modern guinea pigs, this really big guinea pig also had a really long tail that it used for balance. Scientists say this biggest guinea pig that ever lived ate mostly grasses like its tiny modern cousins, just lots more of it of course!
How Big Do Guinea Pigs Get?
We’ve answered your questions about how big do guinea pigs get and how much should a guinea pig weigh. Hopefully, we’ve provided you with lots of other interesting information and facts on guinea pigs as well.
To recap, the average guinea pig weight is 25-40 ounces (700-1100 g) and guinea pig size lengthwise is typically 8-10 inches (20-25.4 cm).
We love guinea pigs for their gentleness, cuteness, wonderful personalities, silky coats, and friendly dispositions. But when you love your guinea pig, you want to learn all there is to know about him or her too!
We encourage you to keep learning, and also to share what you learn with other guinea pig enthusiasts. How big is your guinea pig? Do you have a furry friend that’s on one end or the other of the size range? Tell us about him or her in the comments.
This article has been updated for 2019.
Further Reading and Resources
- American Cavy Breeders Association
- Banks, R. “The Guinea Pig: Biology, Care, Identification, Nomenclature, Breeding, and Genetics.” USAMRIID Seminar Series, 1989.
- Bhattacharya, S. “Buffalo-Sized Guinea Pig Revealed,” New Scientist, 2003.
- Hines, DVM, PhD, R., “Guinea pigs as Pets” 2nd Chance, 2017.
- Hixon, J. “Cavia porcellus: Guinea pig,” University of Michigan, 2011.
- Musser, G. “Guinea pig: Rodent,” Encyclopedia Brittanica, 2017.