One of the most rewarding parts of adopting a kitten is watching them grow up. If you have a kitten at home, you might find yourself wondering when exactly they are going to stop growing and how big they are going to get.

Cats can vary quite dramatically in size, so it can be difficult to tell exactly how large a cat will be or when they are done growing. However, cats have a fairly standard life cycle that you can watch as they get older. Here’s what to watch out for as your cat progresses through their life cycle.

When Do Cats Stop Growing

Cat Life Cycles

While cats can vary in terms of their size and development, they all pass through similar phases of life. These include:


This is the period from birth to 6 months old. During this time, cats are growing very quickly and learning new behaviors.

Junior cat

This is the period from 6 months to 2 years old. In this phase, cats are still very active and need lots of playtime. They aren’t fully mature and still need support and encouragement.

Prime adult

This is the phase from 3 to 6 years old. During this time, cats are generally healthy, active, and confident.

Mature adult

This phase lasts from 7 to 10 years old. In this period, your cat will start to slow down and become less active. They may start to develop health issues and need more care.

Senior cat

Cats reach senior status around 11 years of age. During this time, you’ll need to watch them closely for health issues and keep them comfortable.

When do cats reach their full size?

Cats generally stop growing around 12 years of age, although this can vary depending on factors like their breed, disease, inherited conditions, and their environment. Kittens grow very rapidly in their first six months, but after this they slow considerably, so the change between 6 months and a year is only a small amount. Here are the approximate weights for domestic shorthaired cats of different ages.

<1 week old <4 ounces
7 to 10 days 4 to 6 ounces
10 to 14 days 6 to 8 ounces
14 to 21 days 8 to 12 ounces
4 to 5 weeks 12 ounces to 1 pound
6 to 7 weeks 1 pound to 1 pound, 8 oz
8 weeks 1.5 to 2 pounds
12 weeks 2 to 3.5 pounds
16 weeks 4 to 5 pounds
6 months 6 to 7 pounds

When Do Cats Stop Growing

What factors affect my cat’s growth?

Not all cats grow at the same rate, and there are many different factors that can affect your cat’s growth rate. For example, your cat’s breed can dramatically affect their growth rate. Maine coon cats are known for being abnormally large, and can take 2-3 years to be fully grown. Alternatively, sphinx and Siamese cats will typically be smaller than average throughout their lives.

Cats can also develop medical conditions that affect their growth rate. Just like humans, cats can have dwarfism, which makes them abnormally small. Your cat’s size will also be affected by how much they were fed as kittens. Feeding your cat enough during their early days will help them reach their full size.

How can I tell when my cat has reached his or her full size?

When Do Cats Stop Growing

It can be tricky to tell when your cat is finally fully grown. Although they do most of their growing in their first 6 months, they can still grow in small amounts afterwards.

The best way to tell if your cat has stopped growing is to plot a growth chart using their weights as they grow. A kitten growth chart is like a baby growth chart – by checking your kitten never crosses over into a new centile, you can be more confident they’re gaining in size, not becoming overweight.

You can also measure and weigh them every month. If those measurements stay the same from month to month, it’s safe to say that your cat has stopped growing. However, be aware that a lot of adolescent cats are overweight, so it’s easy to be fooled into thinking your cat is still growing when really they’re getting fat!

When should I stop feeding my cat kitten food?

It’s important to feed your cat kitten food when they are young. Kitten food is specifically formulated for growing bodies and will help them reach their full, healthy potential. Generally, you should switch to adult food when they turn one year old.

Large breed cats like Maine coons may need to stay on a kitten diet for longer. Consult with your vet during that first year to make sure they are growing properly and getting enough nutrition.

The first year of life is most important for your cat’s growth and well-being. Whether your cat is itty-bitty or extra large, the most important thing is that they are healthy and loved!