Guinea pigs vary in size and weight based on several factors, including age, activity level, and gender. Your Guinea pig's breed also plays a role in how large they will grow. Most importantly, your guinea pig's weight can be a good indication of their health.
How Fast Cavies Grow and Adult Size
At birth, most Guinea pigs - also known as cavies - average between 3 and 4 inches long, weighing about 3½ ounces, or around 100 grams. They grow quickly, roughly doubling in size within eight or nine weeks. Growth slows after their initial spurt, and cavies stop growing around 14 months of age.
When cavies reach adulthood, they measure between 8 and 12 inches long on average, and weigh between 1½ to 2½ pounds (24 to 40 ounces), or roughly between 680 and 1,200 grams. As with most other mammals, male Guinea pigs are generally larger than female guinea pigs. Some breeds may even weigh up to 4 pounds (64 ounces), or close to 1,800 grams on average!
Guinea Pig Breed Size Guidelines
Some Guinea pig breeds are larger than others. Although there isn't a large difference in size, weight may vary based on breed. The chart below shows the size of each individual guinea pig breed.
| Guinea Pig Breed | Average Length | Average Weight |
|---|---|---|
| Texel | 8 to 10 inches | 700-1,100 grams |
| American | 8 to 10 inches | 700-1,100 grams |
| Teddy | 10 to 12 inches | 800-1,400 grams |
| Peruvian | 10 to 14 inches | 900-1,400 grams |
| Abyssinian | 8 to 12 inches | 900-1,400 grams |
| Cuy | 8 to 16 inches | 1,800-3,600 grams |
You can weigh your Guinea pig at home using a regular kitchen scale. Set your scale to ounces or grams for a more accurate measurement.
How to Tell if Your Guinea Pig is Overweight
Determining if your Guinea pig is overweight is a difficult task, since every Guinea pig is different. The best way may be to weigh your guinea pig on a weekly basis to understand what their normal weight is once they have reached adulthood. To do this, you will need either a scale that measures weight in ounces or grams. A gram scale is more accurate, overall. Their weight likely won't vary by pounds, but rather by grams, which is why a gram scale is necessary.
If you think your Guinea pig is gaining weight, contact your veterinarian. They will likely conduct an examination to determine if their weight gain is caused by an underlying medical condition. For example, Guinea pigs can get bloat. However, if your veterinarian does not find an underlying medical condition, they may then discuss diet options to get your pet's weight back to normal.
Enclosure Requirements Don't Affect Adult Size
Guinea pigs do not grow to fit their enclosure size. If they don't have enough space, their growth may be stunted. Also, there's a common misconception that Guinea pigs and hamsters can stay in the same size enclosure. However, Guinea pigs actually need more room than the average hamster or gerbil, especially if there's more than one in the enclosure. Also, all Guinea pigs need time outside their enclosure for more exercise.
The sides of your Guinea pig's enclosure should be a minimum of 12 inches high. The top of their enclosure can remain open as long as there are no other animals in the house, such as cats. This can help bring in fresh air, which is necessary for their health. Guinea pigs should never be housed in an aquarium or a habitat with wire flooring as both pose hazards to their well-being.
Ideally, the enclosures should be a minimum size of:
| Number of Guinea Pigs | Minimum Requirement | Recommended Enclosure Size |
| 1 | 30 by 36 inches | 30 by 50 inches |
| 2 | 30 by 50 inches | 30 by 62 inches |
Even though Guinea pigs are social creatures, they still need space for movement. Large enclosures provide an opportunity for more enrichment. Your guinea pig is more likely to live a long life if they remain happy and content in their environment.
Interesting Facts About Guinea Pig Size
There is a lot of variability in Guinea pig adult size, and your pet's breed and sex will determine how large they grow. To keep your cavie as healthy has possible, pay attention to the following:
- Provide a sufficient amount of room can aid in preventing obesity in your Guinea pig.
- Even if you have a large enclosure, your pet should be permitted to roam with supervision for additional stimulation.
- Large enclosures reduce the risk of Guinea pigs fighting if you have more than one in the habitat.
- Keep Guinea pigs together in pairs. Guinea pigs are social animals and enjoy one another's company, but they must have enough room to have their own space when desired.
- Check the enclosure carefully before purchasing it for your Guinea pig to make sure it's safe, especially if you have other pets in the home.
Guinea Pig Size Varies
Although there are generalizations regarding guinea pig size, your individual Guinea pig may be outside of the normal range. They could be smaller or larger. It's important to understand what your individual Guinea pig's normal weight and size is. Observe your Guinea pig regularly, weigh them once per week, and contact your veterinarian if you notice any anomalies.
