Most cats stop noticeably growing around 12 months old, but many keep slowly filling out until about 18 months, and some large breeds can grow until around 2 years old.

Quick Scoop

  • Most average house cats reach their adult size between 12–18 months.
  • Females often finish growing a bit earlier, around 10–12 months, while males may keep growing closer to 18 months.
  • Big breeds like Maine Coons and some other large cats can continue growing up to about 2 years of age (sometimes a bit more in individuals).
  • After that, any “growth” is usually just weight gain rather than getting taller or longer.

If your cat is under a year, you can still expect some noticeable changes; past 18 months, most size changes are very gradual and subtle.

Bottom note: Information gathered from public forums or data available on the internet and portrayed here.