There’s a common misconception that calculating a cat’s age in human years involves simply multiplying the cat’s age by seven. (The same myth about how dogs age has had staying power over the years.)

However, cats actually mature rather quickly in their first two years of life and then their aging slows.

At a year old, a cat is actually 15 in human years, and when the cat reaches 2 years of age, it’s 24 in human years. Upon reaching the “age” of 24, a cat then ages four human years for every calendar year.

So a cat that’s been alive for four years is 32.

Average lifespan depends on many factors though, including the cat’s breed and health. (For a breakdown of average lifespan by breed, visit PetCareRX.)

But one of the best ways to ensure a long life for your feline friend is to keep your kitty indoors.

Indoor cats often live more than 20 years, but outdoor cats — which are more likely to encounter illnesses, predators and busy streets — live half as long.

Not sure how old your cat is?

If you’ve adopted a kitten or an older cat and don’t know the animal’s history, your veterinarian will be able to provide you with an age estimate.

When determining a feline’s age, one of the first things a vet will look at is the cat’s teeth.

Kittens start getting baby teeth around 3 weeks of age, and their permanent teeth come in when the cat is 3 or 4 months old. A cat with a full set of clean, permanent teeth is likely about a year old — or 15 in human years.

If the teeth are beginning to yellow, this indicates the cat may already be about 2 years old, and if there’s tartar buildup or the beginning of gingivitis, the cat could be up to 3 or 4 years old.

Cats that don’t receive dental care will likely develop obvious signs of dental disease from the ages of 3 to 7.

Most cats are considered to be seniors once they reach 7 to 10 years of age, and at this point they may even begin losing teeth.

When determining a cat’s age, you can also look at their overall appearance. Younger cats will be more muscular while older ones may be bonier and have protruding shoulder blades.

Cats’ fur also changes as they age. Kittens’ fur may appear fuzzier, and young, healthy cats will usually have fine, soft coats.

Senior cats’ fur will be coarser and may even change in color, developing light- or gray-colored patches. Cats with longer fur could also develop clumps or mats.

Older cats may also show signs of arthritis and develop cloudy eyes and a raspy voice.

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