How old does a cat need to be to be considered an adult?
A cat is considered an adult at 12 months old. Cats generally go through several stages.
A kitten's kittenhood lasts from 1 to 3 months, which is roughly equivalent to a human's 5th year. A kitten's adulthood lasts from 7 to 12 months, roughly equivalent to a human's 18th or 19th year. Kittens can start eating cat food after they turn one year old. Generally, a cat's lifespan is 13 to 18 years. 
Male cats typically reach sexual maturity at 6-8 months. Female cats typically reach sexual maturity and enter estrus at 8-12 months. The optimal mating age for male and female cats is 13-16 months for females and 12-15 months for males. Although cats have reached sexual maturity, their bodies are not yet fully developed, so while they are sexually mature, they are not yet adults.
When a cat reaches seven or eight years old, it is considered senior. At this time, it will become less responsive and slower in many ways.
