When Do Cats Stop Growing? Kitten Growth Guide

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Getting a kitten is always an exciting time, and watching a kitten develop from a gangly, super-cute ball of fluff into a beautiful, elegant cat is one of life’s true pleasures. Because many cats retain their youthful behaviour well into adulthood, you may wonder: when do cats stop growing and at what age are cats full-grown adults?

When Are Cats Full-Grown?

One day, you have a tiny kitten running around your house, and before you know it, they're a big cat. It may seem like they grow overnight, but cats actually go through six life stages, as explained by International Cat Care in their CatCare for Life initiative. One way to determine when your cat is full-grown is to see into which category they fall:

  • Kitten (0 – 6 months)
  • Junior (7 months – 2 years)
  • Adult (3 years – 6 years)
  • Mature (7 years – 10 years)
  • Senior (11 years – 14 years)
  • Super senior (15+ years)

Much like their human counterparts, the development stages of kittens are counted in weeks and months up until the age of two.

At What Age Do Cats Stop Growing?

At about one year old, your cat will be fully grown. Cats reach adulthood in the junior stage moving into the adult stage. You can think of this as your cat being in their late teens and 20s – young adults full of energy and verve.

Large Maine coon cat lying on a gray couch.As your cat develops into adulthood, your veterinarian can help you determine your cat's ideal weight and recommend a meal plan to help optimise their health. You can work together to modify this plan as your cat moves into each new life stage. It's important to schedule this visit so that these baselines can be established, allowing you to keep an eye on your cat's wellness as they age. Regular check ups also allow you to keep an eye on your cat’s weight and body condition. Keeping your cat slim throughout their life will help them live longer and lowers their risk of certain diseases, such as diabetes.

Pedigree and Mixed-Breed Cats

The vast majority of cats are what we call either domestic short hair or domestic long hair, or just mixed-breed. They’re just beautiful, unique cats of no particular breed. Although there are dozens of breeds of cat recognised around the world, their size doesn’t vary anywhere near as much as dog breeds do. The average cat weighs around 4 kilograms. The Maine Coon is the largest breed of cat and the males can weigh up to 10 kilos and grow to a height of 40cm! On the flip side, the smallest cat breed, the Singapura, weighs at the most 3.5 kilos. Not only is the Singapura smaller, but they also reach adulthood later, around two years of age.

Pedigree cats tend to be more prone to health problems than moggies because they are inbred. So if you do decide you want a pedigree, always make sure you do your research about what issues they may have and always choose a breeder that does all the appropriate health tests. Avoid cats that have extremes of body shape like very flat-faces, tiny legs or hairlessness. These cats can have a very poor quality of life due to their physical characteristics.

If you've raised your cat from a kitten or the junior stage of life, you have a pretty good idea of their temperament and social-emotional needs. You also know their favourite napping spot and favourite toy. As your furry friend grows up, you also want to ensure that they have a well-balanced, nutritious meal plan that's formulated for their age range, so they get the vitamins and nutrients they need. Your veterinarian can help you decide on the most appropriate food throughout all the fascinating stages of your cat’s life.

Contributor Bio

Christine O'Brien

Christine O'Brien

Christine Brovelli-O'Brien, Ph.D., is an award-winning writer, editor, and long-time cat mum. She's a professional member of the Cat Writers' Association (CWA) and has written for industry-leading companies and organizations, including What to Expect When You're Expecting and NIU STEM Read. Find and follow Christine on Instagram and Twitter @brovelliobrien


Reviewed by Dr. Hein Meyer, DVM, PhD, Dipl-ECVIM-CA and Dr. Emma Milne BVSc FRCVS