Cat Growth Calculator
When Do Cats Stop Growing? (Cat Growth Chart by Age)
Enter your cat's age, breed type, and sex to see its current growth stage and estimated full-size age.
Current stage
Rapid growth phase
Your kitten is in the fastest-growing period — most skeletal growth happens now.
Estimated to stop growing: Around 12 months (typically 10–18 months for domestic cats)
When do cats stop growing?
Most cats reach their full adult size by 12 to 18 months. Female cats typically stop growing at 10–12 months, while males may keep growing until 18 months. Large breeds like the Maine Coon can keep growing until 2 years — or even 3–5 years — while small breeds like the Singapura may stop by 9 months. This covers when cats are fully grown, when kittens stop growing, and when cats reach full size.
Cat Growth Chart by Age
| Age Range | Stage | Note |
|---|---|---|
| 0 – 6 months | Rapid growth | Most of a kitten's skeletal growth happens here. |
| 4 – 5 months | Growth plates begin closing | X-rays can start to predict adult size. |
| 4 – 9 months | Sexual maturity | Cats can reproduce before they finish growing in size. |
| 6 – 12 months | Slowing growth | Approaching adult size; adult teeth finish coming in by 6–8 months. |
| 10 – 12 months | Most females reach full size | Typical for domestic short/long-hair females. |
| 12 – 18 months | Most males reach full size | Males often keep filling out longer than females. |
| 2 years | Large breeds reach full size | Maine Coon, Norwegian Forest Cat and similar. |
| 3 – 5 years | Giant breeds may still be filling out | Some Maine Coons keep growing this long. |
Why Do Some Cats Grow Longer?
Breed is the single biggest factor. A Singapura may be done growing by 9 months, while a Maine Coon can keep adding size until 2 years — and some lines until 3 to 5 years. This is why one when do cats stop growing answer does not fit every cat: the number depends heavily on breed. Spaying or neutering matters too, because altering a cat slightly delays the closing of its growth plates, so fixed cats often grow a bit longer and end up slightly larger than intact cats of the same breed.
- Sex: males are usually heavier and keep growing longer than females.
- Sexual maturity vs. size: cats reach sexual maturity at 4–9 months — well before they're done growing in size, which is a common source of confusion.
- Genetics and litter size: genetics and early-life nutrition both influence final adult size.
How to Tell If Your Cat Is Done Growing
- Track weight and length every few weeks — no change over a couple of months usually means growth has finished.
- Check the teeth — adult teeth are usually fully in by 6–8 months.
- Ask your vet to check joints or take an X-ray — growth plates typically begin closing around 4–5 months.
Switching to adult food
Once your cat stops growing, it's time to switch from kitten food to an adult formula — kitten food is higher in calories, protein, and calcium/phosphorus, and staying on it too long can lead to excess weight gain. Vaccine and checkup schedules typically shift at this point too. Once you know when do cats stop growing for your cat, switch from kitten food to adult food to avoid overfeeding a cat that no longer needs a kitten-level calorie count.
FAQ
- When do cats stop growing?
- Most cats reach full adult size by 12 to 18 months. Females typically stop around 10–12 months, while males may keep growing until about 18 months.
- When is a cat fully grown?
- Around 12 months by common veterinary convention, though large breeds may take considerably longer.
- When do Maine Coons stop growing?
- Maine Coons often keep growing until about 2 years old, and some continue filling out until 3–5 years.
- Do male cats grow bigger than females?
- Yes, male cats are typically heavier and continue growing for longer than females.
- Is my cat still a kitten at 12 months?
- Physically, most cats have reached adult size by 12 months, but behaviorally many cats continue maturing through 1–2 years old.