Kitten Details
Results
How Big Will My Cat Get? Guide
Kittens do most of their growing in the first year. This calculator estimates a cat's adult weight from its current age and weight, based on the typical share of adult weight kittens reach at each age.
A kitten is only part-grown at any given age. Dividing current weight by the fraction of adult weight typical for that age gives an estimated adult weight.
A Useful Rule of Thumb
A common shortcut is that a kitten's weight at 16 weeks (about 4 months) roughly doubles to reach its adult weight. Most cats reach close to their full size by 10 to 12 months, though large breeds like Maine Coons keep growing for two years or more.
Kitten Growth by Age
As a guide, kittens reach roughly 18% of adult weight by 8 weeks, 35% by 12 weeks, 50% by 16 weeks, 75% by 6 months, 90% by 9 months, and close to 100% by one year. Breed and genetics shift these numbers, so treat the result as an estimate.
What Affects Adult Size
Breed is the biggest factor — a typical domestic cat settles around 8 to 10 pounds, while some large breeds exceed 15. Sex matters too, as males are usually heavier than females. Nutrition and neutering timing also play a role.
This is a general estimate for information only, not veterinary advice. Every animal is different — always consult your veterinarian for guidance on your pet's health, diet, and care.
Related: Cat Age Calculator, Cat Calorie Calculator, and How Big Will My Dog Get.
Frequently Asked Questions
How big will my kitten get?
Estimate it by dividing current weight by the fraction of adult weight typical for the kitten's age. At 16 weeks, a kitten's weight roughly doubles to adulthood.
At what age do cats stop growing?
Most cats reach close to full size by 10 to 12 months, but large breeds such as Maine Coons can keep growing until two years or older.
How much should a cat weigh?
A typical adult domestic cat weighs about 8 to 10 pounds, though healthy weight depends on breed and frame; large breeds weigh considerably more.
Are males bigger than females?
Yes, male cats are usually heavier and larger than females of the same breed.
Need a Calculator We Don't Have Yet?
Can't find the calculator you need? We'll build it. Submit your request and we'll evaluate it for our growing collection.
Request Calculator