Chinchilla Growth Stages: When Do They Stop Growing?

If you have recently adopted or purchased a chinchilla, you may be wondering how to tell when your chinchilla is an adult. This will help you determine the right cage size for your chinchilla and any future size adjustments you will have to make in the future.

There are two main captive chinchilla species, and each species grows to a different size. Namely the short-tailed chinchilla, and the long-tailed chinchilla. Chinchillas grow quickly, and they should be fully grown by about two years of age. Their growth rate will be influenced by their diet, health and genetics. So when you get a chinchilla, the adult size may be different.


5 Stages of Chinchilla Growth

A chinchilla has about five stages of growth, starting from the gestation period, to the adult stage. A healthy chinchilla with a good genetic background can live an average of 20 to 30 years. However, in the case of chinchillas raised in captivity, between 10 and 18 years is common.

1. Pregnancy

The average gestation period for a chinchilla is 110 to 115 days. The mother chinchilla will carry between 2 and 4 kits during one gestation period. Once she gives birth, the newborn chinchilla is known as a ‘kit’.

2. equipment

They can weigh between 25 to 80 grams at birth and are born with a full coat of fur and eyes open right after birth. A kit is wobbly and unstable after birth, but they soon become more agile a few hours later. They will spend the first few weeks of their lives huddled with their mother for food and warmth. After about 8 to 12 weeks, kits will start to become more mature and independent, however, they are not yet fully grown.

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3. calves

After 2 to 3 months when mothers start reducing the amount of time they breastfeed their kit, they are known as ‘weaning’. They must be separated from their mothers and placed in new cages with same-sex siblings. During this transition, weaning will be stressful and it may take some time to get used to the dietary changes. This can make them appear less round and stocky than when they were breastfed by their mother.

4. teenager

This stage continues throughout most of their first year. At this stage, they are rapidly developing and learning. Male chinchillas can be considered sexually mature after 8 months of age, whereas females will take longer to be considered sexually mature for breeding purposes. Juvenile chinchillas aren’t fully grown yet, but they’re almost there!

5. mature

Around 12 months of age, juvenile chinchillas are considered adults. This is the final stage where they will either slow down their growth or stop growing altogether. They will acquire their plumage and adult size, which can differ between species of individual chinchilla sex.

black velvet chinchilla


How Big Do Chinchillas Get?

Short-tailed chinchillas grow larger and full-grown to about 12 to 18 inches in length. They will weigh between 2 to 3 pounds and have an energetic and active personality.

Long-tailed chinchillas are smaller and are considered full-grown to between 1 and 2 pounds. They can range from 9 to 15 inches in length from head to tail. This is the most common form of domesticated chinchilla in captivity.

You shouldn’t expect your chinchilla to exceed 20 inches, measured from nose to tail. Neither species of chinchilla should grow smaller than 8 inches, which is quite small and unusual.

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When Do Chinchillas Stop Growing?

Both chinchilla species will stop growing between 10 and 18 months of age. Once they reach two years of age, they should stop growing altogether and just ‘fill in’ their weight. Female chinchillas will appear more stocky than males, which can make them appear larger. However, this only applies to weight, and not length.

It completely depends on the genetics, species, and diet of the chinchilla when determining why they have a certain growth rate. Chinchilla fed a healthy, balanced diet, will have a slow and steady growth rate. Meanwhile, chinchillas fed an inadequate diet may struggle to gain weight or absorb essential vitamins and minerals needed for proper growth and development.

pink white chinchilla

Post-Weaning Development

If kittens are weaned too early from their mother, they may not grow much during the first few weeks. This is because their mother’s milk is nutritious and necessary for rapid growth as they enter the weaning or juvenile stage. They should start growing again a few weeks after they are given a milk substitute or other form of healthy diet. They may almost look ‘pygmy’, which can happen to many young rodents that are weaned prematurely. If you have just weaned, make sure that they have been properly separated from the mother in the case of breeders, otherwise they may need a quality milk substitute to start their growth again.

Do Chinchilla Runts Stay Small?

If you think your chinchillas are stunted, you may need to give them extra supplements and milk to help keep them healthy. They may be small and slimmer than the average chinchilla, but this is nothing to worry about. A dwarf can live a long and healthy life, they may just need an extra hand up during the first few months.

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Chinchillas eat cereal flakes



Each chinchilla will have a slightly different growth rate, so don’t worry if your chinchilla grows slower or faster than your partner or sibling. By identifying the species of chinchilla you are keeping, you will be able to determine the average adult size of your chinchilla.

We hope this article has answered your questions about chinchilla growth rates and adult size.

  • Related reading: How Many Babies Does a Chinchilla Have in the Trash?

Featured Image Credit:, Shutterstock

Chinchilla Growth Stages: When Do They Stop Growing?
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