When you first hold a tiny kitten it’s hard to imagine how quickly it will grow. A kitten increases in size rapidly but when you can expect one to stop growing and be considered an adult cat?
Though cats are considered to become adults when they reach 12 months, this is not when they stop growing. A cat may not reach its potential size until 18 months to 4 years of age, depending on a variety of factors including breed.
When will my cat stop growing?
In reality, the age at which cats stop growing varies widely. Breed, genetics, health, and diet all play their part. Broadly speaking, your cat might stop growing once it reaches 12 months but could continue increasing in size until it is 4 years old.
Though many cats reach their maximum length and height by 12 months, they continue to fill out and increase in weight as their muscles develop.
The vast majority of cats finish growing somewhere between 18 and 24 months of age, though many of the larger breeds, such as Maine Coons, keep growing until they are 3 to 4 years old.
It’s important to establish when a cat has finished growing in order to provide the correct nutrition for its life stage.
The best way to know when your cat has stopped growing is by keeping monthly records of its height, length, and weight. When these measurements are continually the same each month, it’s safe to assume your cat has stopped growing!
When do kittens stop growing?
A kitten is not considered to be a cat until it is 12 months old. This is not the age at which it stops growing though so technically you could say kittens never stop growing!
On average kittens of any breed (or crossbreed) are about the same size at birth. Usually, the more kittens in a litter, the smaller each kitten will be.
One thing is certain: kittens grow rapidly. In the first 2 weeks of their lives, kittens experience their largest percentage growth rate because during this time they literally double in weight.
The average weight of a kitten at birth is 5 ounces and by 2 weeks of age is 10 ounces.
Typical kitten growth rates
| Age | Weight range |
| At birth | 5 ounces |
| 1 week | 7 ounces |
| 2 weeks | 11 ounces |
| 3 weeks | 13 ounces |
| 4 weeks | 16 ounces |
| 6 weeks | 1.5 pounds |
| 8 weeks | 1.8 pounds |
| 10 weeks | 2 pounds |
| 3 months | 3 pounds |
| 4 months | 4 pounds |
| 5 months | 5 pounds |
| 6 months | 6 pounds |
| 9 months | 7 pounds |
| 12 months | 8 pounds |
Nutrition in the first ten months is important for a cat’s growth
A common cause of stunted growth in a cat is poor nutrition during the first 10 months of its life.
This often happens with strays and abandoned cats. If you rescue a cat and it appears small, it will soon catch up to its expected size when it is fed a healthy diet, rich in vitamins and nutrients.
If you’ve rescued an underweight cat, be careful not to over-compensate and allow your cat to become overweight in your quest to build it up.
Cats are obligate carnivores – they really need a diet rich in protein from meat. Give your cat the correct food for its life stage at all times. If you choose to make your own, ensure you follow a recipe designed for cats.
A cat really should not be vegetarian but if you insist, speak to a vet to make sure you supplement its diet correctly to make sure it doesn’t miss out on any vital nutrition. this will ensure it grows to a healthy size.
Cat growth in relation to life stage
A cat’s life has 6 life stages:
- Kitten (0 to 6 month)
During the kitten stage, rapid growth occurs.
- Junior (7 months to 2 years)
Whilst it is a junior, a cat continues to grow but at a slower rate. Some stop growing at age 1 and by age 2 most cats have finished growing – though larger breeds often continue to grow beyond this age.
- Prime (3 to 6 years)
By the prime life stage, a cat is generally physically mature. Som may grow a little more but this usually stops by 4 years.
- Mature (7 to 10 years)
Cats in the mature life stage should maintain their size. Any increase that occurs now is often unhealthy weight gain and should be monitored carefully.
- Senior (11 to 14 years)
Cats in the senior stage if life may start to lose weight. Ensure yours has a healthy diet and doesn’t begin to look scrawny. Keep it as active as possible to help maintain muscle strength.
- Super Senior (15 years+)
Super senior cats are usually less active and generally eat less. Don’t let a senior cat become overweight as this will put a strain on its heart, joints, and other organs.
When cats don’t grow as big as expected
Cat’s vary vastly in weight, length and height. Don’y worry if your cat ha a small frame and is a lightweight as long as your cat is happy that it’s healthy.
It is thought that cats who are spayed or neutered at the earliest age possible grow larger than those who have the operation when they are further into adulthood.
Occasionally a cat may have dwarfism and not grow as large as expected. Other bone conditions can also stunt growth.
When cats grow bigger than expected
Just like with people, it is possible for a cat to exceed the average size expected. Many indoor cats gain weight easily due to inactivity.
If a cat is overweight it often has a saggy belly, no visible waist when viewed from above and its ribs aren’t easy to feel.
A naturally large cat will still be the right weight for its frame and won’t be carrying excess fat.
How big do different breeds get?
We’ve looked at the most popular cats and researched their height ranges to create this reference table. All heights are taken from the ground to the nape of the neck. (Source: Dimension Guide)
| Breed | Height in inches (cm) |
| Abyssinian | 8 to 10 (20 to 25) |
| American Shorthair | 8 to 10 (20 to 25) |
| Bengal | 8 to 10 (20 to 25) |
| Birman | 8 to 10 (20 to 25) |
| Devon Rex | 10 to 12 (25 to 30) |
| Maine Coon | 10 to 16 (24 to 40) |
| Persian | 8 to 10 (20 to 25) |
| Ragdoll | 9 to 11 (23 to 28) |
| Siamese | 8 to 10 (20 to 25) |
| Sphynx | 8 to 10 (20 to 25) |
When Do Cats Stop Growing?Conclusion
It’s difficult to put an exact age on when a cat will top growing simply because this varies from breed to breed and even for cats within the same breed.
Many cats are fully grown by 18 months but larger breeds, such as Maine Coons can grow until they are 4 years old.
The only thing that can be guaranteed is that all cats eventually stop growing – unless you overfeed them!