When do cats stop growing? Understanding your household pet's life stages. – USA TODAY

Our feline friends go through changes everyday just as we do, like losing baby teeth. But unlike some humans, cats do not have to wait until they are 18 years old to be considered full grown. 
While still young, the age of a kitten can be determined by weight. For each month, a kitten will generally gain one pound, according to PetMD. So, it would not be incorrect to assume a 3-pound kitten is three months old. However, this estimate only works until a cat is six months old. 
As your cat gets older, it continues to grow. But, when do cats stop growing?
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Cats tend to stop growing once they become 1 year old. A 12-month-old cat is approximately the same age as a 15-year-old human, says PetMD.
However, some cats do continue to grow past the 12 month mark. Cats are considered “full-grown” when they reach 18 months, which is equivalent to the age of a 21-year-old human, according to PetMD. 
Between the span of those 12 to 18 months, a cat can continue to grow in size. Some breeds do not even reach full size until they are 2 years old, says PetMD. For example, Maine coon cats are fully grown by around two  years, according to PetMD. 
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There are some growth differences between male and female cats, according to dutch.com. 
Male cats stop growing later in life and grow at a slower rate than female cats, says dutch.com. Male cats also tend to be larger than female cats. 
Female cats hit puberty earlier than male cats do, and unlike their female counterparts, once male cats “stop growing and reach sexual maturation, they do not go into heat,” according to dutch.com. 
Adult male cats will often exceed or exactly reach the higher ranges of length, height and weight for their breed, according to the happycatsite.com. For instance, male Bengal cats can weigh up to 22 pounds, though the breed’s normal weight is around 16 pounds. 
Additionally, male cats of smaller breeds will reach full size before male cats of larger breeds, says happycatsite.com. 
Cats are be mischievous little creatures, scratching and clawing their way through the world. While your cat continues to grow in size, so it does in behavioral and social maturity, says PetMD. 
Once a cat reaches 2 years old, it will be more socially and behaviorally mature, according to PetMD. 
When kittens are younger, they tend to be social and active, “spending copious amounts of energy playing and generally acting crazy,” says Figo Pet Insurance. 
But as they adapt to their environment and form a routine, cats become relatively calmer, says Figo. 
As much as we love to call our pets babies, they stop being them at one point. For cats, their days as kittens last until they are one year old, according to Hill’s Pet Nutrition. After that point, kittens become cats.
Though cats are considered adults at 12 months, adolescence lasts until around 18 months, according to Hill’s Pet Nutrition. 
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