How to Convert Cat Years to Human Years

The idea of cat or dog years is really not as simple as it seems on first sight. For starters, cats mature faster than humans do, which means that kittens get older much faster (in human years) than they do as adults.

We humans have long gestation periods and care for our young for many years. Kittens are born after 66 days (give or take) and need much less care compared to our own babies. Matching cat years to human years is, therefore, not linear.

At first, they age rapidly, adding 1.5 human years every month during the first 6 months of their life. For the next 6 months, you add 1 human year each. When they are 1 year old, kittens count 15 human years. Maturity is reached by the time they are 2 years of age, which corresponds to 24 human years. From this point forward, you add 4 human years per year for indoor cats, and 8 years for outdoor cats. If your cat is both indoor and outdoor, you add 6 years. Due to less exertion and fewer injuries, indoor cats live longer than outdoor cats.

Trying to convert the age of one species to that of another is no exact science. Because of this fact, there are alternative measures for this conversion.

If you want to calculate your cat’s age directly, simply enter your cat’s age into this calculator.

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The oldest cat ever known was Nutmeg, a male from the UK that died on August 29th, 2017 at 32 years of age. Being an indoor cat, Nutmeg was 144 human years old. Yikes!

For completion and quick reference, here is a chart that includes the first year of your cat’s life as well.

Cat Years Chart

Cat's Age

Indoor Cats

Indoor & Outdoor

Outdoor Cats

1 Month

1.5 Human Years

1.5 Human Years

1.5 Human Years

2 Months

3 Human Years

3 Human Years

3 Human Years

3 Months

4.5 Human Years

4.5 Human Years

4.5 Human Years

4 Months

6 Human Years

6 Human Years

6 Human Years

5 Months

7.5 Human Years

7.5 Human Years

7.5 Human Years

6 Months

9 Human Years

9 Human Years

9 Human Years

7 Months

10 Human Years

10 Human Years

10 Human Years

8 Months

11 Human Years

11 Human Years