a ginger and white maine coon lookign at the camera

When Do Maine Coons Stop Growing?

The Maine Coon is one of the largest cat breeds in the world.

They can grow up to a hefty 20lbs quite frequently, but that isn’t their only trick.

They grow into adults at a slower rate than other breeds, and as such will become fully grown much later than is normal for a cat.

So, to begin with, what’s the deal? When does a Maine Coon stop growing?

A Maine Coon won’t stop growing till they are around 3 to 4 years of age, but after 18 months most of the growth has taken place. They require kitten food till around 15 to 18 months rich in protein sources to grow healthily.

There’s so much to learn about these big balls of fur.

Maine Coon in grass close up

How Long Until A Maine Coon is Fully Grown?

While there are a lot of variables at play answering this question, like genetics and diet. It’s likely that a Maine Coon will only stop growing when it’s around 3 or 5 years old.

Some males have continued to grow until they are 5, but how much of an increase in size might be more to do with diet than anything else.

So, if you are used to ‘normal cat breeds’ that stop growing after a year, then buckle up, because you might be in for a 5 year trip.

If you plan for 3 to 4 year growth then you won’t be far wrong.

It’s largely down to genetics. If the parents were large cats then all other things being equal you might be looking at a small tiger yourself.

A Maine Coon can continue fur growth as well, so it may be a case of the fur getting bushier, not an increase in the frame of your Maine Coon.

Neutered cats can also stop growing a little earlier as well, and there is some evidence that neutering increases the likelihood of weight gain.

You certainly can’t tell the age of a Maine Coon by its apparent size relative to another Maine Coon.

a maine coon standing proud outside

How Big Is A Maine Coon At 1 Year?

This will depend upon not only genetics but gender.

A female Maine Coon will be smaller than the male counterpart all other things being equal.

Maine Coons are on average 115g at birth and will put on around 1lb in weight every month.

Thus, in a year, it’s quite possible to have a 12lb cat on your hands.

That’s already 2lb heavier than an average cat in weight. They still have a few years of growth as well.

One year after birth a Maine Coon will continue growing till 15 to 18 months after birth when the rate will slow.

They will then continue growing, although much more slowly for another few years.

a maine coon nose sniffing the air

Things That Can Stop A Maine Coon From Growing

A Maine Coon will stop growing around the age of 3 or 4.

Factors like food intake, care (breed and health), as well as other environmental effects can affect their growth rate but they most commonly stop growing around their third year.

Maine Coons are often given kitten food until 15 to 18 months after birth due to the fact that they are still growing.

Kitten food for Maine Coons contains a high protein rich diet so that they can grow into a full grown adult.

It is more common for them to stop at about 18 months though because their organs and other systems have matured enough that it doesn’t need as much protein after those years.

As well as genetics there are a few factors that contribute to stunting a Maine Coons growth.

Malnourishment – lack of calories doesn’t necessarily mean the owner isn’t feeding their pet enough calories. Parasites and worms can take a lot of the nourishment provided in the food.

Regular worming checks can help along with a veterinarian checkup that looks at whether your Maine Coons weight is normal.

Allergies – This one is close to my heart.

My Maine Coon, Alita, is on the smaller side for a Maine Coon. She would eat a lot but not put on too much weight.

The reason? She is allergic to chicken.

She is allergic to animal proteins in chicken, turkey, and duck. Feeding her these protein rich foods means she does not take in the required calories.

Thus if you are feeding your Maine Coon a regular diet and it isn’t growing, try changing the protein source, from chicken to fish for example.

Taking off kitten food too soon – Kitten food is protein rich to complement the growing needs of a Maine Coon.

A Maine Coon kitten will grow at a similar rate from birth to 15 to 18 months. Thus they need kitten food for slightly longer than normal breeds.

Alita the Maine Coon on the table

Protein rich foods help with health and growth during the early stages, and putting a Maine Coon too early on normal food that would be low in proteins might stunt growth slightly.

Cheap cat food – low cost cat food is often more grain based rather than based on animal proteins.

This leads to a lack of protein in your Maine Coons diet which has similar results to taking a Maine Coon off kitten food too early.

Stressful environment – A cat can get stressed for a variety of reasons. Sometimes it’s the presence of another cat, sometimes it’s just that they have moved houses.

Stress, among other illnesses, can cause a lack of appetite and thus stunt growth.

Neutering – Although this doesn’t actually stunt a Maine Coons growth, current thinking is that neutering early in a cat’s life makes the bones fuse later which can make a Maine Coon look taller or longer than those spayed later on in life.

Alita the Maine Coon head


The Maine Coon, although a large cat breed is still a kitten at heart for a while after it looks like it’s stopped growing.

Whilst most cats will be adults after 1 year old, the Maine Coon is still a kitten really 15 to 18 months after birth.

I still find the fact that they can carry on growing for 4 years after birth a little bit astonishing, but that’s what the vet’s told me.

So Alita is still growing, and that I find amazing. She is still small for a Maine Coon though.

Regardless of any of the facts about Maine Coon growth, the fact is you will have an amazing breed of cat, full of fun and loyalty.

About the Author


My name is Ann and I have been looking after and breeding cats since 2013. I am currently the proud ownder of Alita, a female Maine Coon to whom I've dedicated this site. She has had 2 litters and is around 3 years old. We share adventures and stories together.

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Maine Coon 101 | Read This Before Getting One