Most cats are fully grown once they reach around 12 months. By then they have attained their adult height and length, and the rapid growth of kittenhood is usually complete. But the answer to when a cat is fully grown depends greatly on the breed. An ordinary domestic cat is typically fully developed by the age of one, while the very large breeds take far longer to reach their final body. That is precisely why it is not age alone, but also the body's development and the breed's temperament, that you should keep an eye on when assessing whether your cat is still growing or has become an adult.

The difference matters in practice. A cat that is still growing needs a different nutritional profile than an adult cat, and the transition from kitten to adult should happen at the right time. Below we go through when the different types of cats are fully grown, how you can tell on your own cat, and what it means for the meals you serve every day.

When is an ordinary domestic cat fully grown?

For the vast majority of cats, physical growth is complete around the age of one. A domestic cat of mixed origin or a breed of normal size has usually reached its adult height and body length by the time it turns one year old. The muscles may still fill out a little in the months afterward, and male cats in particular may become somewhat sturdier in body, but the skeleton itself is typically finished.

Sexual maturity often comes before full physical maturity. Many cats become sexually mature as early as five to seven months of age, that is, long before they are fully grown. This is an important distinction, for a cat can easily behave like an adult, appear sexually mature, and yet still be growing physically. If you are in doubt about whether your cat has finished growing, the vet is the best person to assess it based on the cat's condition and any X-rays.

Mentally, maturation also takes time. A cat of one year may still have much of the kitten's playfulness and energy left, and for many cats the youthful behavior continues well into their second year of life, even though the body has long since become adult.

Large cat breeds grow for several years

The large breeds stand out markedly when it comes to the pace of development. A Maine Coon, a Norwegian Forest Cat, a Ragdoll or a Savannah typically takes several years to reach its final size. The Maine Coon is known for growing all the way up to four or five years of age, where it continues to put on weight and fill out in both body and coat. This means that a two-year-old Maine Coon can easily look adult and yet have several years of development left.

The reason is quite simply that there is more body to be built. A larger skeleton, more muscle mass and a heavier coat take longer to develop, and the large breeds are therefore a good example of the fact that age alone does not determine when a cat is fully grown. If you have a kitten of a large breed, it is wise to expect a longer growth period and to plan feeding accordingly.

Conversely, there are breeds and individuals that are small and quickly fully grown. Wherever your cat falls on the scale, it is the combination of breed, sex and the individual cat's build that paints the overall picture. If you are unsure what to expect of your particular breed's development, it can be worthwhile to ask your breeder or vet.

How to tell whether your cat is still growing

The clearest sign of an adult cat is that its size remains stable over time. If you weigh your cat at regular intervals, at some point you will find that the weight no longer increases due to growth, but stays constant. This is often the most tangible signal that the cat has reached its adult body.

The body shape also changes. The kitten typically has a somewhat angular, long-limbed appearance, where paws and ears can look large relative to the rest of the body. As the cat matures, the proportions become better balanced, and the muscles fill out so that the body takes on a more harmonious and finished look. In male cats, heavier cheeks may also develop.

Behavior is a softer indicator. Many cats gradually become more subdued and routine-oriented as they move from young to adult, although the desire to play can easily continue throughout life. If you use these signs together, you get a far more accurate picture of where your cat is in its development than if you look only at the age on the calendar.

How long should a cat have kitten food?

As long as the cat is growing, it needs meals that support growth. As a rule of thumb, you give kitten meals up until around the age of one, when most cats are fully grown, and then switch to adult meals. A kitten needs a higher content of energy and the nutrients that build the body, while an adult cat thrives best on a nutritional profile adapted to a more stable life.

For the large breeds, the timing shifts. If your cat is still growing, as is often the case with the Maine Coon and the other large breeds well into their second year of life and beyond, there may be reason to stick with the nutrient-dense diet for longer. Here it is the development and not the calendar that should govern when you switch, and your vet can help you hit the right time for your particular cat.

For the youngest cats we have gathered nutritious cat meals in our meals for kittens, while you will find the adult alternatives among meals for adult cats. If you are in doubt about when and how best to make the transition, ESSENTIAL FOODS' nutrition advisers are ready by phone, chat and email to advise you on feeding, food and nutrition, so that your cat gets the right meal for its life stage.

How to switch from kitten to adult meals

The switch itself should happen gradually. The cat's digestion does best with calm and predictability, and a sudden switch from one meal to another can cause an upset stomach. If you mix the new adult meals in with the familiar kitten meals over a period of about a week and increase the proportion of the new one little by little, you give the digestion time to get used to the transition.

Once the cat has become an adult, the energy requirement also changes. An adult cat living a quiet indoor life burns less than a young cat in full growth, and it is therefore important to adjust the amount so that the weight stays stable. Keep an eye on the cat's body condition along the way, and adjust the portions so that it neither loses weight nor puts on unnecessary weight.

ESSENTIAL FOODS' meals for cats are prepared from fresh produce and human-grade ingredients and composed with the cat's natural needs in mind. In the collection of cat meals you will find the exquisite meals gathered in one place, where you can choose based on your cat's life stage, taste and daily wellbeing. Whether your cat has just become an adult or is still growing, it is the right nutritional profile for its particular age that provides the best foundation for a healthy cat life.