Cat years to human years: age chart and how to calculate it

The short answer: to convert cat years to human years, count a cat's first year as about 15 human years, its second as about 9 more, and each year after as about 4.

• 1 year: about 15 human years
• 2 years: about 24
• The old seven-to-one rule is not accurate
• Life stages: kitten, young adult, mature adult and senior
• Next step: Plan it with the Pet Health Records ($5.49).

To convert cat years to human years, count a cat's first year as about 15 human years, its second as about 9 more, and each year after as about 4. Cornell's Feline Health Center explains in its guide to senior cats that the old seven-to-one rule is not accurate, and puts a one-year-old cat at about 16 and a two-year-old at 21, adding about four years each year after that. Below is a full age chart, the life stages vets use, and what care each stage needs. Every cat is an individual, so treat the numbers as estimates.

Cat years to human years chart

The first column uses the conversion found on most veterinary age charts (15 at one year, 24 at two, then 4 per year). The second uses Cornell's figures (16, 21, then about 4 per year). The life stage comes from the 2021 AAHA/AAFP Feline Life Stage Guidelines.

Cat age chart for kittens, by month

Kittens grow up fast, so the first year is easier to read in months. This is the commonly used veterinary age chart for the first two years:

The 2021 AAHA/AAFP guidelines note that kittens can be weaned onto kitten food from 3 to 5 weeks, and that a growing kitten needs far more calories per pound than it will at 10 months.

How old is my cat in human years? Look it up by birth year

If you know the year your cat was born, find it below. Ages are counted for 2026, so if your cat's birthday has not come yet this year, use the row for one year younger.

For a cat adopted as an adult, use the age your shelter or vet estimated at adoption and add the years since.

Using a cat years calculator

A cat years calculator does the same arithmetic as the chart, so you can do it in your head:

1. Start with 15 for the first year.
2. Add 9 for the second year (24 total), or 6 if you use Cornell's figure of 21.
3. Add 4 for every year after that.

Example: a 9-year-old cat is 24 + (7 x 4) = 52 on the vet chart, or 21 + (7 x 4) = 49 on Cornell's. No calculator accounts for breed, weight or illness, so treat any result as a rough guide to life stage rather than an exact age.

How the formula works

Cats grow up fast. A kitten goes from newborn to fully grown in about a year, which is roughly the same development as a person reaching the mid-teens. By two, a cat is a young adult in its early twenties. After that, aging slows to about four human years per cat year.

To work it out yourself:

1. If your cat is 1, call it about 15.
2. If your cat is 2, call it about 24.
3. For older cats, take the age, subtract 2, multiply by 4 and add 24.

Example: a 9-year-old cat is (9 − 2) × 4 + 24 = 52 in human years.

Cat life stages and what each needs

The AAHA/AAFP guidelines group a cat's life into four age-based stages plus an end-of-life stage that can happen at any age. They note the cutoffs are guides, not hard rules, and that individual cats vary a lot.

Cornell notes that many cats start to show physical changes of aging between 7 and 10, and most do by 12. The guidelines highlight obesity prevention in young adults and closer watching for kidney disease in mature and senior cats.

Signs your cat is getting older

• sleeping more and playing less;
• weight loss or weight gain without a diet change;
• drinking more water or using the litter box more;
• stiffness jumping up to favorite spots;
• changes in grooming, coat or appetite;
• confusion, crying at night or changes in personality.

Cornell points out that age itself is not a disease. Many conditions in older cats cannot be cured but can be controlled when they are caught early. Bring any of these changes up with your vet rather than putting them down to "just old age."

Keeping records as your cat ages

The changes that matter in an older cat are often slow: a few ounces of weight a month, a little more water each week. They are easy to miss without notes. Writing down weight, vaccines, medications and each vet visit gives you and your vet a clear picture.

The Pet Health Records ($5.49, printable PDF) has a Pet profile, Vet & emergency contacts, Vaccination Record, Vet Visit Log, Medication & Preventives, Weight Tracker, Feeding & care routine and Pet sitter instructions page. Print a set for each cat. If you prefer a bound book that lasts for years, the Pet Health Record Book (Paperback) is a 6 x 9 inch, 120-page version small enough to take to the vet. It isn't on Amazon yet; its page has a Notify me button for one email when it can be ordered.

Weight and body condition at every age

Vets track weight, body condition score and muscle condition at every visit, because the trend matters more than any single number. The 2021 guidelines use a 9-point body condition scale: 6 or 7 out of 9 counts as overweight and 8 or more as obese. Middle-aged cats tend to gain weight, while being underweight is a common problem in senior cats.

Play helps at every age. In one study cited by the guidelines, three 10- to 15-minute play sessions a day led to a loss of about 1% of body weight in a month, without cutting food.

Writing your cat's weight down at each visit, or weighing them at home every month, makes a slow change easy to spot.

How cat years compare with dog years

Dogs and cats both age fast in their first two years. After that, cats age at a fairly steady pace, while dogs age at different speeds depending on size, with large breeds aging faster. That is why a single cat chart works for most cats, while dog charts are usually split by weight.

Making the most of every stage

• Kittens: keep up with the vaccine series; see our kitten vaccine schedule.
• Young adults: weigh your cat every month or two and keep treats small.
• Mature adults: ask about baseline blood work so later tests have a comparison.
• Seniors: add ramps or steps, keep litter boxes easy to reach and book checkups more often.

For dogs in the family, see our dog vaccines guide and the dog vaccination record page.