Cat years to human years

To convert cat years to human years, count a cat’s first year as 15 human years, the second as 9 more (24 in total), then add 4 human years for every year after that. So a 4-year-old cat is about 32 in human terms, a 10-year-old is about 56, and a 15-year-old is about 76.

That is the conversion International Cat Care uses. It is a rough guide rather than an exact science, but it is far closer than the old “times seven” rule. For a quick answer, try the cat age calculator.

Cat age chart

Cat’s age	Human age
1 month	0–1
3 months	4
6 months	10
1 year	15
18 months	21
2 years	24
3 years	28
4 years	32
5 years	36
6 years	40
7 years	44
8 years	48
9 years	52
10 years	56
11 years	60
12 years	64
13 years	68
14 years	72
15 years	76
16 years	80
17 years	84
18 years	88
19 years	92
20 years	96
25 years	116

Source: International Cat Care.

Why kittens age so fast

In the first year a kitten goes from a helpless newborn to a sexually mature, almost full-grown cat. Many can have kittens of their own from around 4 to 6 months. That is a human childhood and adolescence squeezed into one year, which is why the first year counts for 15 and the second for 9 more.

After about 2, a cat is a grown adult and ages more steadily: about 4 human years per cat year for the rest of their life.

Why not seven?

The seven-year rule is a loose comparison of average lifespans. For cats it is badly off at both ends: it makes a 1-year-old cat a 7-year-old child when they are really a teenager, and it makes a healthy 16-year-old cat 112 when they are closer to 80. Breed, genes, weight, lifestyle and health all shift how fast a particular cat ages, so treat any human-age figure as an estimate.

Cat life stages

Two sets of life stages are in common use, and they broadly agree.

International Cat Care

Life stage	Cat’s age	Human equivalent
Kitten	0–6 months	0–10 years
Junior	7 months–2 years	12–24 years
Adult	3–6 years	28–40 years
Mature	7–10 years	44–56 years
Senior	11–14 years	60–72 years
Super senior	15 years and over	76 and over

AAHA and AAFP (used by many vets)

The 2021 AAHA/AAFP Feline Life Stage Guidelines use four stages, plus an end-of-life stage that can happen at any age:

Life stage	Cat’s age
Kitten	birth to 1 year
Young adult	1 to 6 years
Mature adult	7 to 10 years
Senior	over 10 years

The guidelines stress that these are “arbitrary demarcations along a spectrum”. A very fit 11-year-old may still be cared for like a mature adult.

What each stage means for your cat

Kitten (to 1 year). Vaccines, worming, neutering and socialisation. The kitten vaccination schedule and new kitten checklist cover the essentials.

Young adult (1 to 6). Your cat is in their prime, roughly a person from their late teens to around 40. The main job now is preventing problems: keeping them lean, looking after their teeth, keeping up with boosters (see the adult cat vaccination schedule) and a yearly check-up.

Mature adult (7 to 10). Your cat is middle-aged, like a person in their mid-40s to mid-50s. The AAHA/AAFP guidelines say this is when vets should start screening for age-related problems such as kidney disease and dental disease, usually with blood and urine tests.

Senior (over 10). Roughly a person in their late 50s to 70s. The guidelines recommend a vet visit at least every 6 months. Watch for weight loss, drinking more, changes in litter box use and reluctance to jump. Our senior cat care guide covers what changes and how to help.

Super senior (15 and over). Like a person in their late 70s and beyond. Many cats reach this stage and some show few signs of it. Keep litter boxes, food, water and beds close and easy to reach, keep up the regular check-ups, and let them set the pace.

Indoor and outdoor cats

Where your cat lives doesn’t change the conversion, but it can change how long they live. Indoor cats avoid road traffic, fights and many infections, and tend to live longer on average. Outdoor cats can still live long lives, especially when neutered, vaccinated and kept up to date with parasite control. Whatever their lifestyle, regular check-ups are what catch the slow, quiet illnesses of older cats early.

Don’t know your cat’s real age?

If you adopted an adult cat, your vet can estimate their age from their teeth, eyes, coat and muscle condition. Kittens are easy to age from their teeth; adults are much harder, so expect a range of a few years rather than an exact number. Pick a best guess, and use it to decide when to start senior check-ups.