Guinea Pig Size & Weight Chart

Guinea pigs are undoubtedly among the cutest animals you can choose for your pet. Their delightful wheeking calls, big pig noses and unique walks endear them to almost everyone.

Owing to their cuteness, it is almost impossible not to spoil your guinea pig with lots of attention and treats. Plenty of toys, lots of attention and large cages are wonderful options for showing love to your pet guinea pig.

Even so, if you are not careful with the edible treats and foods you give your pet, you might go overboard. This leads to having an excessively fat guinea pig. To some pet owners, fat guinea pigs are adorable and happy animals, but they are not healthy animals.

However, with body shapes that look like rounded bricks, it is challenging to tell whether or not your guinea pig is fat so that you can prevent obesity and the issues associated with it in your pet.

Below are guidelines on a guinea pig’s weight and size to ease your care of a healthy animal.

Guinea Pig Size and Weight Chart

To ease your understanding of the size and weight to expect in your pet guinea pig at different stages, consider the table below:

Age Size Weight
Birth 3-4 in 2-4 oz
2 months 6-8 in 6-8 oz
4 months 8-10 in 12-16 oz
6 months 8-11 in 19-22 oz

– Newborn

At birth, a guinea pig usually measures 3-4 inches though you can expect some natural size variation among the animals in your litter. The number of pups in your litter will also affect how big each of the newborns will be.

In general, large litters produce small offspring. This makes sense when you consider that there is less room for growth when there are more babies in a sow. The average litter size in guinea pigs is 1-6 pups with three pups in a typical birth.

– Juvenile

Guinea pigs will grow quickly and double their size to 6-8 inches at around eight weeks. After this, your pet’s growth will somewhat slow, but the animal will still become somewhat larger within a short time.

It reaches 8-10 inches after about 16 weeks with about four times its birth weight. At about seven months, a guinea pig will have reached about 50% of its adult weight.

– Adult

Guinea pigs continue growing until they reach about 14 months old though it might not look like they are changing much after 16 weeks. In adulthood, you can expect your pet to weigh 1000-1200g (35-42 ounces) with females weighing slightly less than males.

Their body sizes at this point are 8-12 inches {20-30cm}. At this time, guinea pigs are considered fully grown, so do not expect them to grow any larger. In the past, it was common to get guinea pigs above their average adult weights.

This has changed with most animals now smaller than average because most people are breeding underage animals.

When Does A Guinea Pig Become An Adult?

A guinea pig, in general, becomes an adult when it turns fourteen months old. This information coupled with its expected weight and size might seem inconsequential.

Even so, if you are getting your guinea pig from a pet store, sometimes the seller might be a bit unsure about its age. In this instance, it is helpful to have some background knowledge of the expected weight of the animal at different ages.

This way, you can avoid buying a pet that is too young for sale. Furthermore, with a knowledge of the weight and size to expect at fourteen months, you can also assess whether your guinea pig is under or overweight and act appropriately to avert different issues.

Can A Guinea Pig Get Fat?

Yes, guinea pigs can get fat. Unfortunately, determining whether your pet is fat or not is not so easy because of the animal’s body shape. Using a gram scale is your best choice for determining whether your guinea pig is overweight.

Weighing the animal regularly will help you keep track of its weight and pick any abnormalities. Furthermore, if you notice your furry friend becoming lethargic with bulging sides, these might be hints of becoming too fat.

To help a guinea pig shed excess weight, promote its exercise with toys and a large cage for free space to walk around. Consider cutting back on fruits and treats as well because these contribute to weight gain.

Remember that excess weight in guinea pigs strains their joints, hearts and livers. It also increases the animal’s risk of certain cancers, breathing issues and diabetes.

Why Is Your Guinea Pig Skinny?

Having a skinny guinea pig is as serious as keeping an overweight pet. Minor weight fluctuations like those around 5% of expected weight are nothing serious, more so if you take your pet’s weight after it has been to the toilet, for instance. Even so, if you notice a loss of 10% of your guinea pig’s weight, it is time to consult a vet.

Some of the common reasons for weight loss in guinea pigs include environmental changes, infections, exposure to temperature extremes, stress, liver disease, dehydration and dietary changes.

During your vet consultation, questions will center on your pet’s medical history and lifestyle before performing a physical exam.

Though you might have an idea of what is causing weight loss in your guinea pig, remember that this is also a common symptom of serious conditions that need treatment.

Wrap Up

Though the above information will ease the work involved in maintaining a healthy weight in your guinea pig, you should be careful when tweaking different elements to achieve a healthy weight.

For example, do not make sudden changes to the pet’s diet so that it loses or gains weight. A few fussy animals will stop eating altogether when there are sudden dietary changes. When they stop eating, this causes a condition known as gastrointestinal stasis that needs medical intervention.

As such, change the diet gradually so that the animal becomes slowly accustomed to the foods. Furthermore, always consult your vet before eliminating or adding food to a guinea pig’s diet.

avatar Jane
Jane is an experienced animal care specialist with a focus on rodents and small mammals, with over 10 years of experience in the pet industry. Her articles provide practical guidance on choosing the right pet and managing common health issues. Jane is an advocate for animal welfare and supports organizations dedicated to protecting wildlife. read more...

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