If you have a cat for a pet and want to know how many candles to stick on its next birthday cake, you can't count its age in human years. You have to translate them into cat years.
Estimate how old your cat is. This will be easy if you got the cat as a kitten. If not your vet can estimate how old the cat is by looking at its teeth and other body parts.
Step2
Your cat develops physically and sexually within the first 12 months of its life life. A human reaches this point at approximately 15 years old. So add 15 human years to your cat's age for the first year of its life.
Step3
Add another 9 human years to your cat's life on your pet's second birthday. Your cat has reached the maturity of a person age 25.
Step4
Add 4 human years to the cat's age for each birthday the two of you celebrate after your cat's second birthday.
Tips & Warnings
This is not a fool-proof method. Some cats mature slower and therefore will not reach full development for 3 or 4 years.
Cats are like people, they age depending on their diet, exercise habits and care. Take good care of your cat and it will live a long life.