How Big Do Guinea Pigs Get? Knowing Your Pet (Guinea Pig's Proportions)

Ayan Banerjee
Feb 25, 2023 By Ayan Banerjee
Originally Published on Nov 10, 2021
Edited by Katherine Cook
Fact-checked by Sonali Rawat
Funny guinea pig eating grass
Age: 3-18
Read time: 7.5 Min

How big do guinea pigs get?

Let us learn about guinea pigs first. They are a rodent species from the genus Cavia and belong to the family of Caviidae.

Guinea pigs have tiny limbs, a small body size, big round eyes, and protruding incisors giving them an adorable and charming look. They have similarities in looks with rabbits. The most surprising fact is guinea pigs neither have any relation to pigs nor their origin is from Guinea. They have origins in the Andes mountains in South America. Guinea pigs are herbivorous in nature. They mostly eat fruits and vegetables of different kinds. Cavies can eat fresh and raw fruits and vegetables that provide them with lots of health benefits because they are rich in vitamin C and other essential nutrients. For example apple, bell pepper, cabbage, carrot, and blueberries. They are very popular household pets in America and European countries, but pet owners must have proper knowledge about them in order to take proper care of these little animals.

Learn more amazing and interesting facts about why do guinea pigs purrandhow to bathe a guinea pig here at Kidadl!

How big is a full-grown guinea pig?

Guinea pigs are attractive small-sized household pets loved by most people. But, what is their exact size?

Fully grown guinea pigs typically grow 8-12 in (20-30 cm) in length and range between 1.5-2.6 lb (700-1200 g) in weight. If we compare guinea pigs to hamsters, they grow to around 2-4 in (5.5-10 cm) in length, which may be equal to a baby guinea pig. They are large in size when compared to house rats or mice. It is obvious that the size of a guinea pig depends on several things. The size varies for males, females, and babies of this species of mammals. They do not have a tail, else it would be difficult to estimate the length and weight of guinea pigs.

How long until a guinea pig is fully grown?

After mother guinea pigs give birth to the small pups, the growth of these young guinea pigs stops at the age of 14 months old. On gaining maturity, these cavies grow 8-12 in (20-30 cm) in length and can weigh up to 2.6 lb (1200 g). This is only average measurements, some guinea pigs may be smaller or larger after the age of 14 months old.

A guinea pig is not considered to be an adult before six months of age. They attain proper maturity only after a period of six months. But that does not mean that they will physically grow for six months. The growth rate slows down as they get closer to the age of 14 months. It is difficult to estimate the age of your pet guinea pig if you have not taken care of it since when it was a baby. After their growth stops, guinea pigs remain the same size all throughout their life. A slight growth in length is possible, but that is a negligible amount.

Little black and white guinea eating cabbage leaf

How big are baby guinea pigs?

A baby guinea pig is 10 times more cute and adorable when compared to an adult guinea pig. The pups do not stay babies for too long, therefore only the breeders are lucky enough to see these tiny guinea pig babies who are the adult version we all love.

Pet animals stores have a guinea pig that is already adult and big in size, so getting to see a newborn guinea pig is a very rare event. You may be wondering, what is the size of guinea pig pups? A baby guinea pig may only be 3-4 in (8-10 cm) big at birth. The weight of a baby guinea pig after birth measures between 2-4.5 oz (60-130 g) which can vary between different breeds. The average weighy of the offspring is 2.8 oz (80 g). The size of baby cavies depends on the size of the litter. The bigger the litter is, the smaller the baby cavy will be. The litter can range from one to eight cavies. The average number of litter sizes tends to be three. Generally, a young guinea pig can grow very fast. In just a span of eight weeks, a newborn guinea pig will grow double in size as well as weight. The baby cavy will be an adult guinea pig in just one year (52 weeks), both in size and weight.

Factors Affecting The Size Of Guinea Pigs

There are many factors, depending on which the size of the guinea pig matters. The first factor being the sex of the cavy. It is possible to identify a guinea pig's sex as either male or female when it reaches the age of three weeks.

Female guinea pigs tend to be 25-30% smaller than males, both in length and weight. You can even differentiate between a female guinea pig and a male guinea pig by palpating it in the abdomen area of its body. Females mostly are at the smaller range of the particular breed, having an average length of 8-10 in (20-25 cm). Male guinea pigs are also called boars, while females are called sows. The males grow to the breed's maximum length. For instance, we can consider an Abyssinian guinea pig size to be between 8-12 in (20-30 cm). But the males of this breed are far more likely to measure a full 12 in (30 cm) in length when compared to the females. This is a genetic factor, which your cannot control for your pets. There are other factors that are related to the size of your guinea pig including feeding a healthy diet to your guinea pig, physical exercise and movements, and also the cage size. These are the factors that you can control to ensure that your guinea pig has a healthy life.

Does the size of the guinea pig depend on the breed?

Now that we know about the factors, on with the growth of your pet cavy depends, let us know in detail about how the size of guinea pigs depends on the breed. As we can see different dog breeds are different in size. Some have small while some are huge. Some can be fat while some are thin.

Just like other animals, the size of guinea pigs also vary depending to their different breeds. Although, there is not actually any big size variety among the guinea pig breeds. The cavy is similar to the breed of rodents and has a small-sized body. Generally, all guinea pig breeds can have a growth measuring around 12 in (30 cm) in length at most after one year of age. Only the rex guinea pig breed after the age of one year can grow up to 17 in (43 cm) in length. Even if the name is rex, this breed is similar to a teddy guinea pig. Rex guinea pigs are considered giants when compared to other breeds of guinea pigs. But that does not mean that if you pet a rex guinea pig, it will grow up to 17 in (43 cm) in length. Abyssinian guinea pigs can measure between 8-12 in (20-30 cm). A little smaller breed is the American guinea pig that can grow up to 8-9 in (20-22.86 cm).

How to ensure your guinea pig reaches its full-size potential?

Now let us talk about how you can help your pet guinea pig to reach its full-size potential. You must remember that you can only check you are giving your pet a nutritious diet, regular health care, and a good size cage for your pet animal. It is important for you to ensure that your pets have a healthy as well as a happy life.

The diet of your pet animal must be full of nutrients and essential minerals. A health-conscious diet for your cavy must include good quality hay along with fruits and vegetables like lettuce, cabbage, bell peppers, and spinach served in moderation. The food must contain vitamin C as guinea pigs cannot synthesize it on their own. They are herbivores and their frontal teeth grow throughout life. Access to clean water is important for them to stay hydrated. It is important to remember that even if your guinea pig is big in size, that does not mean that its health is good. Do not overfeed hay to your pets and make sure they regularly exercise to avoid obesity and related health problems.

The housing cage of guinea pigs also plays an important role in their physical growth. It is mandatory that they have a room with a big space that they can run around in. Rodent animals enjoy a big-sized cage as they can play around and also have enough movement helping to digest food and grow physically. Lastly, as guinea pigs are social animals, they would enjoy the company of other guinea pigs in the big space of their cage and it is healthy for them to stay with partners.

Here at Kidadl, we have carefully created lots of interesting family-friendly factsfor everyone to enjoy! If you liked our suggestions for how big do guinea pigs get then why not take a look at can guinea pigs have bananas or guinea pig facts.

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Written by Ayan Banerjee

Bachelor of Science specializing in Nautical Science

Ayan Banerjee picture

Ayan BanerjeeBachelor of Science specializing in Nautical Science

Thanks to his degree in nautical science from T.S. Chanakya, IMU Navi Mumbai Campus, Ayan excels at producing high-quality content across a range of genres, with a strong foundation in technical writing. Ayan's contributions as an esteemed member of the editorial board of The Indian Cadet magazine and a valued member of the Chanakya Literary Committee showcase his writing skills. In his free time, Ayan stays active through sports such as badminton, table tennis, trekking, and running marathons. His passion for travel and music also inspire his writing, providing valuable insights.

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