Cat Age Calculator
A cat's age in human-equivalent years and its life stage, on the veterinary chart: fast growth in the first two years, then about four human years for every cat year.
The first cat year is worth about 15 human years and the second about 9 more (24 by age two).
How the cat age calculator works
The first cat year is worth about 15 human years and the second about 9 more (24 by age two). From then on each cat year adds about four human years, so a 10-year-old cat is roughly 56. The life stages are the AAFP feline stages: kitten to six months, junior to two, prime adult to seven, mature to eleven, senior to fifteen, then geriatric.
Formula: Human years = 15 × age (to 1) · 15 + 9 × (age − 1) (to 2) · 24 + 4 × (age − 2) (after)
How cat years convert to human years
Fast at first, then steady
Cats don't age at a constant rate, so the old "one cat year equals seven human years" shortcut is simply wrong. Kittens rocket through childhood and adolescence, then settle into a slower, steadier pace. The widely used feline chart puts year 1 at about 15 human years and year 2 at about 24 — so a two-year-old cat is already a young adult. From then on, each additional cat year adds roughly four human years. Crucially, and unlike dogs, a cat's breed and size barely change the maths: a petite Siamese and a big Maine Coon age at much the same rate.
Worked example
A 5-year-old cat is about 36 in human years — 24 for the first two years, plus three more years at +4. A 10-year-old cat is about 56, and a 15-year-old is around 76. A cat that reaches 20 — not unusual for a pampered indoor cat — is roughly 96 in human terms. Switch the calculator to the Standard level or higher to see the full milestones table.
This is a general guide, not a health check. Human-equivalent age is a helpful way to think about life stage and what care a cat needs, but individual cats vary. Your vet's assessment always overrides this tool — especially for kittens, seniors, or any change in appetite, thirst, weight or behaviour.
Feline life stagesThe life stages behind the number
Vets group a cat's life into stages that line up with the human-equivalent age. Knowing the stage tells you what to watch for:
- Kitten (0–6 months) — up to ~10 human years. Explosive growth and learning; the time for vaccinations, socialising and planning neutering.
- Junior (6 months–2 years) — ~15 to 24 human. Fully grown in body by the first birthday, still boisterous and adolescent.
- Prime adult (3–6 years) — ~28 to 40 human. Physically at their peak; the age to establish a healthy weight and an annual vet check.
- Mature (7–10 years) — ~44 to 56 human. Middle age — weight can creep up and it's worth watching for early signs of common conditions.
- Senior (11–14 years) — ~60 to 72 human. Time for twice-yearly checks and attention to kidneys, thyroid, joints and teeth.
- Geriatric (15+ years) — ~76 human and up. Extra comfort, warmth and monitoring; many cats reach this stage in good shape indoors.
The stage shown in your result comes straight from the age you enter, so it updates as you change the number — a quick way to sense-check where your cat sits.
Lifespan, indoors and careHow long cats live — and how to add years
Indoors vs outdoors
Lifestyle is the single biggest lever on how long a cat lives. Indoor cats commonly reach 15–18 years and often well beyond, while cats that roam outdoors face traffic, fights, disease and predators and average far shorter lives. Keeping a cat inside, or giving it safe outdoor time in a secure run or catio, can add the human-age equivalent of decades. Neutering, vaccination, parasite control and dental care all stack the odds toward a long, healthy life.
Kittens grow up fast
By six months a kitten is roughly a 10-year-old child, and by its first birthday it's about a 15-year-old teenager — fully grown in body if not in judgement. That's why cats can breed from around 4 months, well before they look grown up, and why neutering is usually recommended by then.
Caring for an older cat
As cats move into their senior and geriatric years, small adjustments help: keep food, water and litter easy to reach, provide warm resting spots, offer softer food if teeth are failing, and monitor appetite, thirst and weight — changes in these are often the first sign something needs a vet's attention. Twice-yearly check-ups catch age-related conditions early, when they're most manageable.
Frequently asked Frequently asked questions
Where these figures come from
The conversion here is the mainstream feline ageing chart used by veterinary and cat-welfare organisations. It is a well-established rule of thumb rather than a country-specific rule, so it applies to cats everywhere.
- Age conversion — year 1 ≈ 15 human years, year 2 ≈ 24, then about +4 human years per cat year (the standard feline chart used by vets and by charities such as International Cat Care and Cats Protection).
- Life stages — kitten, junior, prime adult, mature, senior and geriatric, following the widely used feline life-stage framework.
- Lifespan — indoor cats commonly reach 15–18 years and often beyond; outdoor-roaming cats average far shorter lives.
- Kitten development — cats can reach sexual maturity from about 4 months, which is why neutering is generally recommended by around 4–6 months.
- Further guidance — RSPCA — pet care guidance.
Last checked: July 2026. This is a general guide, not veterinary advice. Individual cats vary with health, breed and lifestyle — for anything about your cat's wellbeing, follow your own vet's assessment, especially for kittens, seniors, or any change in appetite, thirst, weight or behaviour.
Understanding your resultSelect the question that matches where you are right now.
The headline number is your cat's age translated into human-equivalent years, using the standard feline chart. The breakdown adds the life stage and, at the Standard level, an ageing milestones table so you can see how the years add up.
What to do with itUse it to picture where your cat is in life — a young adult, middle-aged or a senior — and to line up the right care, from an annual check-up in the prime years to twice-yearly checks later on.
What it is notIt's not a health assessment or a prediction of lifespan. Two cats the same age can be in very different shape depending on genetics, weight, lifestyle and care.
Why not just ×7The ×7 rule badly underestimates a young cat and overstates the pace later. Cats front-load their ageing — 15 human years in the first cat year alone — so a proper chart is far more accurate.
Only a couple of things really move a cat's human-equivalent age and lifespan — and breed isn't one of the big ones.
Age does the workThe conversion is driven almost entirely by age: fast for the first two years, then a steady +4 human years each cat year after that.
Breed barely mattersUnlike dogs, where a Great Dane and a Chihuahua age very differently, cats of all breeds and sizes age at much the same rate.
Lifestyle sets the lifespanIndoor living, neutering, vaccination and dental care are what stretch a cat's life to 15–18 years and beyond — the age conversion stays the same, but a safe lifestyle means far more of those years to convert.
Match the care to the life stage the number points to.
Kitten & juniorVaccinate, socialise and plan neutering by around 4–6 months. Growth is fast, so keep up with vet checks and feed for healthy development.
Prime & matureSet a healthy weight and an annual check-up. Watch for creeping weight gain, which is easy to miss in a comfortable indoor cat.
Senior & geriatricMove to twice-yearly checks, keep food, water and litter easy to reach, and monitor appetite, thirst and weight for early warning signs.
A cat is one line in the household budget. Model the wider cost of a pet and how it fits your outgoings.
The whole householdSee how food and pet care fit your monthly running costs.
Cost of living → Fit it in the budgetSlot food, litter and vet bills into a monthly plan.
Budget planner → A buffer for the vet billBuild a rainy-day fund for the unexpected vet visit.
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How cat years work Year 1 = 15, year 2 = 24
Cats age fastest in their first two years. By its first birthday a kitten is roughly a 15-year-old human, and by two it's about 24 — already a young adult. After that, each cat year adds about four human years. So the '×7' shortcut is wrong for cats too: a two-year-old cat isn't 14, it's closer to 24. Breed and size have little effect, unlike in dogs.
| 1 cat year | ≈15 human |
|---|---|
| 2 cat years | ≈24 human |
| Then | +4/yr |
- Breed effect Minimal
- ×7 rule Wrong
How old is a 5-year-old cat? ≈ 36 human years
A 5-year-old cat is about 36 in human years — 24 for the first two years, plus three years at +4. That's a cat in its prime: physically mature, settled in temperament, and usually at its healthiest. It's a good age to establish a baseline with an annual vet check and keep an eye on weight, since indoor cats can gain weight quietly in their prime years.
| Human age | ≈36 years |
|---|---|
| Life stage | Prime adult |
| Watch | Weight gain |
- Annual check Set a baseline
- Health Usually peak
Is a 10-year-old cat old? ≈ 56 human years — mature
A 10-year-old cat is about 56 in human years — mature, heading toward senior, but often with many good years ahead. This is the age to move to twice-yearly vet checks and watch for the common older-cat conditions: kidney disease, overactive thyroid, arthritis and dental problems. Early detection makes all of these far more manageable, and many cats live well into their late teens.
| Human age | ≈56 years |
|---|---|
| Life stage | Mature |
| Vet checks | Twice a year |
- Watch for Kidney, thyroid
- Many Good years left
Senior and geriatric cats Senior from ~11 (60+)
Cats are considered senior from around 11 (about 60 in human years) and geriatric from 15 (about 76). A 20-year-old cat — not unheard of indoors — is roughly 96 in human terms. Senior cats need warmth, easy access to litter and food, softer diets if teeth are failing, and closer monitoring of appetite, thirst and weight, which are the first signs something needs a vet's attention.
| Senior | 11+ (≈60) |
|---|---|
| Geriatric | 15+ (≈76) |
| 20 years | ≈96 human |
- Monitor Appetite + thirst
- Comfort Warmth, easy access
Indoor vs outdoor cat lifespan 15–18+ vs far less
How long a cat lives depends hugely on lifestyle. Indoor cats commonly reach 15–18 years and often beyond, while cats that roam outdoors face traffic, fights, disease and predators and average far shorter lives. In human-age terms, keeping a cat indoors (or in a cat run/enclosure) can add the equivalent of decades. Neutering, vaccination and dental care further stack the odds toward a long life.
| Indoor | 15–18+ years |
|---|---|
| Outdoor | Much shorter |
| Add | Neuter + vaccinate |
- Indoors Adds years
- Enclosure Safe outdoor time
Kitten to adult, fast 1 kitten month ≈ human toddler
Kittens develop at a sprint. By six months a kitten is roughly a 10-year-old child, and by its first birthday it's a 15-year-old teenager — fully grown in body if not yet in judgement. That's why kittens seem to go from tiny to teenage almost overnight. It's also why neutering is recommended around 4–6 months: cats can breed from about that age, well before they look 'grown up'.
| 6 months | ≈10 human years |
|---|---|
| 1 year | ≈15 human years |
| Neuter | ~4–6 months |
- Fast growth First year
- Can breed From ~4 months
Worked examples
| Inputs | Human-equivalent age | Note |
|---|---|---|
| A 3-year-old cat | 28 human years | 28 human years, prime adult |
| A 10-year-old cat | 56 human years | 56 — mature |
| A kitten of six months | 8 human years | about 8 human years |
FAQFrequently asked questions
How old is my cat in human years?
Cats age fast at first, then steadily. By its first birthday a cat is roughly a 15-year-old human, and by two it's about 24 — already a young adult. After that, add about four human years for every cat year. So a 3-year-old cat is about 28, a 5-year-old about 36, and a 10-year-old about 56. The old "×7" rule doesn't work for cats. Breed and size make little difference to the maths, unlike in dogs.
How old is a 10-year-old cat?
A 10-year-old cat is about 56 in human years — 24 for the first two years, plus eight years at about +4 each. That's a mature cat heading toward senior, but often with many good years ahead. It's a sensible age to move to twice-yearly vet checks and to watch for common older-cat conditions such as kidney disease, an overactive thyroid, arthritis and dental problems.
When is a cat a senior?
Cats are generally considered senior from around 11 years — about 60 in human terms — and geriatric from about 15 (roughly 76 in human years). A 20-year-old cat, which is not unheard of indoors, is around 96. Senior cats benefit from warmth, easy access to litter and food, softer diets if teeth are failing, and closer monitoring of appetite, thirst and weight.
Do indoor cats live longer?
Yes — by a wide margin. Indoor cats commonly reach 15–18 years and often beyond, while cats that roam outdoors face traffic, fights, disease and predators and average far shorter lives. Keeping a cat indoors, or giving it safe outdoor time in a secure run or catio, can add the equivalent of decades in human-age terms. Neutering, vaccination and dental care improve the odds further.
How fast do kittens grow up?
Very fast. By six months a kitten is roughly a 10-year-old child, and by its first birthday it's about a 15-year-old teenager — fully grown in body if not yet in judgement. That rapid development is why neutering is recommended around 4–6 months: cats can breed from about that age, well before they look grown up. Sources
The sources behind this calculator
- American Association of Feline Practitioners — Feline Life Stage Guidelines — the six feline life stages the cat-age page uses
- Wang et al. 2020, Cell Systems — Quantitative translation of dog-to-human aging by conserved remodeling of the DNA methylome — the 16·ln(age)+31 epigenetic formula on the dog-age page
- UK Government — Tips at work — the law on how tips are shared with staff
Last checked: September 2026. Where a page states a convention (a tipping custom, a pet life stage), the page names the body it follows.