From the first tentative steps as as a kitten right through to grand old age, watching your cat develop is a wonderful, rewarding experience.
In his early development, there will of course come a time when he stops growing. So how do you teel when your cat is fully grown?
This is around 12 months according to most experts. But some cats reach full size from 18 months to as much as five years of age, as is the case with larger breeds such as the Siberian.
As we’ll see, much depends on the breed of your cat.
How to Tell if Your Cat is Fully Grown
The most reliable way to tell if your cat is fully grown is by weighing at least twice a month.
When the weight remains within the 12 – 14 pound range, this signals that your cat has reached full size.
However,there are a couple of things you’ll need to consider here.
Gender
Gender can have an impact on cat size, with males usually heavier and bigger than females (sometimes as much as 15%).
Often though, the differences aren’t really all that pronunced. In general, both sexes tend to weigh
between 6 and 12 pounds, stand about 8 – 10 inches high and measure 10 – 16 inches from nose to tail.
Breed
Breed is the biggest factor that can determine a cat’s size, as well as the age it becomes fully grown.
The table below explains the average age that the most common housecat breeds reach full-size.
Average height, length and weight are included too. The data takes into account both genders.
| Breed | Fully Grown Age | Av. Weight | Av. Height | Av. Length |
|---|---|---|---|---|
| Norwegian Forest | 5 Years | 12 - 16 lbs | 9" - 12" | 12" - 18" |
| Siberian | 5 Years | 10 - 20 lbs | 10" - 12" | 17" - 25" |
| Turkish Van | 5 Years | 10 - 20 lbs | 10" - 14" | 14" - 17" |
| Maine Coon | 4 - 5 Years | 8 - 25 lbs | 10" - 16" | 19" - 32" |
| Ragamuffin | 4 Years | 10 - 20 lbs | 10" - 15" | 12" - 18" |
| British Shorthair | 3 - 5 Years | 9 - 17 lbs | 12" - 14" | 22" - 25" |
| American Shorthair | 3 Years | 10 - 15 lbs | 8" - 10" | 12" - 15" |
| Ragdoll | 3 Years | 10 - 20 lbs | 9" -11" | 17" - 21" |
| Savannah | 3 Years | 12 - 25 lbs | 14" - 17" | 20" - 22" |
| Persian | 2 Years | 7 - 12 lbs | 10" - 15" | 14.5" - 17.5" |
| Birman | 3 Years | 10 - 12 lbs | 8" - 10" | 15" - 18" |
| Himalayan | 2 Years | 8 - 12 lbs | 10" - 12" | 17" - 19" |
| Bengal | 18 Months - 2 Years | 10 - 15 lbs | 8" - 10" | 16" - 18" |
| Cheetoh | 18 Months - 2 years | 12 - 25 lbs | 12" - 18" | 17" - 21" |
| Napoleon Cat | 18 Months | 5 - 9 lbs | 7" - 8" | 12" - 14" |
| Scottish Fold | 12 Months | 6 - 12 lbs | 8" - 10" | 14" - 16" |
| Sphinx | 11 - 13 Months | 6 - 12 lbs | 8" - 10" | 13" - 15" |
| Siamese | 10 - 12 Months | 8 - 15 lbs | 8" - 12" | 11.5" - 14" |
| Abyssinian | 6 - 12 Months | 6 - 10 lbs | 12" - 16" | 12" - 16" |
Can You Predict How Big Your Cat Will Get?
There’s no 100% accurate method for predicting when cats stop growing.
But to get a rough idea of your cat’s adult weight, some experts suggest weighing your cat at 16 weeks and then doubling it.
Considering the genetic differences between breeds, the result should however be treated as a ballpark figure.
The Growth Stages of Cats
Another way to get an idea of when your cat will stop developing physically, is to familiarise yourself with the early life stages of a feline. There are generally four stages.
If we take into account the maturation ages detailed in the above table, we need to use the first three life stages: Kittens (up to 6 months), Junior (6 months to 2 years) and Young Adult (2 to 6 years).
Kittens (Up to 6 Months)
The 0 – 6 month stage is when a cat develops fastest, with most kittens growing around eight times their size in just eight weeks.
At this point a kitten will typically weigh between 1 and a half to 2 pounds.
By 16 weeks, this will have increased to approximately 3 pounds.
As the kitten rockets toward junior cat status, he’ll probably be around 8 to 15 pounds. These changes will be noticeable too with the young cat looking leaner and more muscular.
Junior (6 Months to 2 Years)
It is at this stage that a kitten’s physical development begins to slow.
Highly active and boisterous, the young feline will likely experience growth spurts leaving him looking rather lanky and long! But he’ll soon fill out as his first birthday approaches.
At 12 months, most Siamese cats, Scottish Folds and Sphinxes are at full-size.
The same goes for Russian Blues as well, although some can take up to 18 months to develop fully. By 2 years, the majority of Persian cats are fully grown.
Young Adult (2 to 6 Years)
In his prime and healthy, your cat will be doing what most cats of do at this stage of their lives, namely hunting, roaming their territory and sleeping!
If your kitten is a smaller breed, it’s highly likely that he’ll be at full-size by about two or three years.
At four years, most Maine Coons are at fighting weight as are Ragamuffins.
For larger breeds such as Siberians, Turkish Vans and British Shorthairs, the growing process probably won’t cease until around the five year mark.
Final Thoughts
As you can see, determining when cats stop growing isn’t an exact science.
There are a number of influencing factors including gender and breed.
Because of genetics, there’ll be going slight differences between felines of the same breed too.
So an approximation is the best you can hope for in calculating when your cat will stop growing.
Remember that a healthy diet can play a major role in the growth, development and body composition of a cat.
