Cat Years to Human Years Calculator

How old is my cat in human years?

Enter your cat's age in years and months and the calculator converts it with the most common cat-age rule. The first year of a cat's life counts as 15 human years. The second year adds 9, so a two-year-old cat comes out at 24. After that, every cat year adds 4 human years. Months count in proportion, so a cat of one year and six months lands at 19 and a half.

Cats grow up quickly, which is why the first two years are weighted so heavily. A one-year-old cat is often compared to a teenager, and the 15 reflects that, not any measurement of your particular cat.

A few worked examples

• 1 year: 15 human years
• 2 years: 24 human years
• 5 years: 36 human years
• 10 years: 56 human years
• 15 years: 76 human years
• 18 years: 88 human years
• 20 years: 96 human years

Indoor cats and outdoor cats

The calculator treats every cat the same. Lifestyle can change how long a cat lives, but it does not change this conversion, and the tool does not try to predict a lifespan. If you are wondering how long your own cat might live, that is a question for your vet, who knows its history.

Life stages

Many cat life-stage charts divide a cat's life into kitten, junior, prime, mature, senior and geriatric stages. The age ranges differ from chart to chart, so this calculator does not draw those lines. It gives you the human-year equivalent and leaves the labels to you and your vet.

What the number is not

It is a conversion of a number, not an assessment of your cat. It is not a "health age", and it does not say whether your cat is behaving normally for its age. If you notice a change in your cat's appetite, weight, thirst or behavior, talk to your vet instead of relying on a number from a calculator.