Cat's Age	In Human Years
1 month	5 to 6 months
2 months	9 to 10 months
3 months	2 to 3 years
4 months	5 to 6 years
5 months	8 to 9 years
6 months	10 years
8 months	13 years
1 year	15 years
2 years	24 years
4 years	32 years
6 years	40 years
8 years	48 years
10 years	56 years
12 years	64 years
14 years	72 years
16 years	80 years
18 years	88 years
20 years	96 years

 

Most cats will reach about 11 or 12 years of age. Few make it to 18 and a very few make it to 20 and older. This depends if it is an indoor cat or an outdoor cat.. Outdoor cats live about 8 years.  Indoor cats often reach 15 or more. Cat years compared to human years, (from material provided by the Gaines Research Center), cats will age 15 years in the first year (10 years in the first six months!) and 4 years for every year thereafter. Some veterinarians say 20 years for the first year, 4 years for each year thereafter.