Last Updated: 03/06/2026
When Do Kittens Stop Growing? A Kitten Growth and Weight Guide
When do kittens stop growing, and how big will yours get? Our vet guide covers the average timeline, a kitten growth and weight chart by age, large breed differences, and how to tell if your kitten is on track.
Author: Dr Gillian Hill BVSc (Hons)
Reading Time: 3 minutes - short read
Kittens grow fast, and it can be hard to know whether yours is on track or how much bigger they are going to get. This guide covers when most cats reach their full size, what the numbers should look like at each age, and what to do if something seems off.
When is a kitten fully grown?
Most domestic cats reach their full adult size at around 12 months of age, though large breeds such as the Maine Coon can keep growing until 15 to 18 months or even longer. The fastest growth happens in the first six months, when kittens roughly double their weight every few weeks. After that, growth slows and most cats are at or close to their adult size by 12 months.
Kitten growth and weight chart
The table below shows average weight ranges for a domestic cat from birth to 12 months. Males tend toward the higher end of each range, females toward the lower. Large breeds will sit above these averages throughout.
The most important thing is not the number itself but the trend. Kittens should gain weight consistently week by week.
Newborn
85-115g
8 weeks
800-900g
3 months
1.0-1.5kg
4 months
1.5-2.0kg
5 months
2.0-2.5kg
6 months
2.5-3.0kg
9 months
3.0-4.0kg
12 months
3.5-5.5kg
Do some breeds take longer to grow?
Yes, though perhaps not in the way you might expect. Large breeds like the Maine Coon, Ragdoll and Norwegian Forest Cat generally reach skeletal maturity at a similar time to other cats, but they keep adding body mass, muscle and coat beyond that point. Many do not reach their full adult weight until 18 months to three years of age, and some Maine Coons continue to fill out even further.
If you have one of these breeds, it's generally recommended to stay on kitten food for longer until around 15 months of age. You may want to ask your vet when it makes sense to switch from kitten to adult cat food.
What affects how big my kitten will get?
- Breed and genetics: the biggest factor. Kittens from larger parents tend to grow larger, and mixed-breed cats usually follow a similar timeline to small or medium domestic cats.
- Sex: males are generally larger and heavier than females, with the gap widening from around six months onward.
- Nutrition: a complete and balanced kitten diet supports healthy, steady growth. Look for a food that meets AAFCO or FEDIAF growth standards.
- Desexing timing: cats desexed very early may develop slightly longer limbs, as sex hormones play a role in when growth plates close. This is a minor effect and does not meaningfully change final size. See our Cat Desexing Guide for more information about timing and the procedure itself.
Is my kitten growing normally?
The clearest sign of healthy growth is a steady upward trend in weight, with a good body condition: ribs palpable but not visible, a slight waist from above. If your kitten is eating well, active and gaining weight consistently, they are almost certainly on track.
Check with your vet if your kitten has stopped gaining weight or is losing it, or you are unsure whether a large-breed kitten is progressing as they should.
The first year of kittenhood is covered in detail in our kitten stages of development hub. If your kitten has just come home at eight weeks, our 8-week-old kitten guide covers what to expect, and if they are around the three-month mark and full of energy, our 3-month-old kitten guide explains what is going on.
Kitten Growth FAQs
Most kittens are fully grown at around 12 months, with the fastest growth in the first six months. Large breeds like the Maine Coon, Ragdoll and Norwegian Forest Cat usually take longer to reach their full weight. The most important thing is a steady upward trend in weight, a good diet matched to their age, and a vet check if anything seems off.
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History
Our experts continually monitor the health and wellness space and we update our articles when new information becomes available.
Thu 4 Jun 2026
Written by Dr Gillian Hill BVSc (Hons)Dr Gillian Hill BVSc (Hons)
Veterinarian
Dr. Gillian graduated from the University of Sydney in 2005 with a Bachelor of Veterinary Science. She worked in a number of small animal clinics, before joining the Pet Circle Vet team in 2020. Dr. Gillian has special interests in ultrasonography, surgery and behaviour. Her favourite part of being a vet is being an advocate for the animals. She loves helping owners to make the best, evidence-based decisions for their pets, and seeing the beautiful bond that people have with their fur-babies.
