How Big Will My Cat Get Calculator
Estimate your kitten's adult weight based on their current age and weight.
Formula
Adult Weight ≈ (Current Weight ÷ Age in Weeks) × 52
- Most cats reach adult weight by 52 weeks (1 year).
- Large breeds (Maine Coon, Ragdoll) may continue growing until 2–4 years.
- Spaying/neutering before 6 months may increase adult size slightly.
3 lb kitten at 12 weeks
Inputs
- Kitten Age: 12 weeks
- Current Weight: 3 lbs
(3 ÷ 12) × 52 = 13 lbs → Large cat.
Frequently asked questions
At what age is a cat fully grown?
Most cats reach full size by 1 year; large breeds by 2–4 years.
Is this formula accurate for all breeds?
It works well for mixed-breed cats. For known pedigree breeds, breed standards are more reliable.