CollarCat Growth Calculator: How Big Will My Cat Get?
Wondering how big your kitten will get? Estimate your cat's adult weight and size from its current age, weight, and breed type, shown as an honest range.
Cat Growth Calculator
Enter your kitten's details to estimate its adult size.
How the Cat Growth Calculator Works
Kittens reach a fairly predictable share of their adult weight at each age. This calculator uses the percentage-of-adult-weight method: it looks up how much of its adult weight a kitten has typically reached at its current age, then works backwards to the full-grown figure.
Adult weight ≈ current weight ÷ (% of adult weight reached)
A kitten is roughly 50% of its adult weight around 4 months, about 80% by 30 weeks, and usually full-grown by 12 months. Because every cat is different, the result is shown as a range.
Large, Slow-Maturing Breeds
Breeds such as the Maine Coon and Ragdoll keep growing until 2 to 4 years old, so at a given age they are further from their final size. For these breeds the estimate is a lower bound: your cat will likely end up heavier and keep filling out well past its first birthday.
Weigh your kitten
Enter its current weight in pounds or kilograms.
Add age and breed type
Give the kitten's age and whether it is a large, slow-maturing breed.
Read the range
See the estimated adult weight, a likely range, and when it should be full-grown.
Frequently Asked Questions
Answers to the most common questions about your kitten's growth.
You can estimate a cat's adult weight from the percentage of adult size it has reached for its age. A kitten reaches roughly 80% of its adult weight by about 30 weeks and is usually full-grown by 12 months. Dividing the current weight by that percentage projects the adult weight, shown here as a range.
Most cats reach their adult size between 12 and 18 months. Females often finish by 10 to 12 months and males a little later. Large, slow-maturing breeds such as the Maine Coon and Ragdoll can keep growing until 2 to 4 years of age.
The most useful clues are the kitten's current weight and age (used here), the size of the parents, and the breed. For a mixed-breed kitten, the parents' adult weight is the best guide. This tool gives a range, not an exact figure, because genetics and sex cause a lot of variation.
A typical domestic cat weighs about 8 to 10 lb (3.6 to 4.5 kg), but healthy weight varies a lot by breed. Small breeds may weigh 5 to 7 lb, while large breeds like the Maine Coon can reach 15 to 25 lb. Your vet can tell you the ideal weight for your cat.
Sources & Further Reading
The growth figures on this page reflect published veterinary averages. To go deeper, visit these trusted references: