Cat Age Calculator

human age = 15 × cat age below one year; human age = 15 + 9 × (cat age − 1) between one and two years; human age = 24 + 4 × (cat age − 2) above two years; the life stage comes from whole calendar months, so a cat on its first birthday has already left the kitten stage

birthDate

The day the cat was born. A date in the future is rejected, because a cat that has not arrived has no age yet

catYears

The cat's age as a decimal number of years: days lived divided by 365.2425, the average length of a Gregorian year. This is the figure the conversion is applied to

catMonths

Whole calendar months lived. The life stage is decided by this figure rather than by catYears, so a cat exactly one year old reads 12 months and is already a young adult

catDays

Days from the birth date to today, counting the leap days in between

humanYears

The cat's age expressed in human years, rounded to one decimal place. It is an approximation, and the two organisations that publish one do not agree

stage

The life stage the cat has reached. The bands are kitten, young adult, mature adult and senior, taken from the 2021 AAHA/AAFP feline life stage guidelines

Use it when you want to know how old your cat is in human terms: bringing home a rescue with an unknown history, filling in a form that asks for the age of a pet, or working out whether a cat has reached the point where the vet wants to see it twice a year instead of once. It is also the quickest way to settle an argument about how old is my cat in human years. The life stage is the part worth reading twice, because it is what the care guidance is written against and it changes years before a cat looks old. The conversion also disposes of the old rule of thumb that one cat year equals seven human years, which understates the first two years badly and overstates the later ones.

1. A cat born 15 January 2022, read on 15 January 2026

   1. 15 January 2022 to 15 January 2026 is four calendar years, which is 1461 days once the leap day in 2024 is counted
   2. As a decimal age that is 1461 divided by 365.2425, which is 4.0001 years
   3. Four years is past the second birthday, so the third stage of the rule applies: 24 + 4 × (4.0001 − 2) = 32.0
   4. 48 whole months, so the cat sits above the 7-year mark and is a mature adult

   This is the shape of answer most people want: a four-year-old cat is around 32 in human years, which is the age of a person who is well into adult life but nowhere near old. The 7-year rule would have said 28, which is the same ballpark by luck rather than by method — it agrees here and disagrees badly at both ends.

2. A kitten born 15 October 2025, read on 15 January 2026

   1. 15 October 2025 to 15 January 2026 is three whole calendar months, which is 92 days
   2. 92 divided by 365.2425 is 0.2518 years
   3. That is inside the first year, so the first stage applies: 15 × 0.2518 = 3.8
   4. Three months is below the 12-month line, so the stage is kitten

   A kitten of three months is a human toddler of about four. The first year is where the conversion earns its keep: a rule of one cat year to seven human years would have said 1.8, roughly half the real figure, and the whole point of the page is that this is the stretch where a cat changes fastest.

3. The day before a 10th birthday: born 16 January 2016, read on 15 January 2026

   1. 16 January 2016 to 15 January 2026 is 3652 days, one day short of ten full years
   2. 3652 divided by 365.2425 is 9.9989 years
   3. 24 + 4 × (9.9989 − 2) = 56.0, so the human-age row already reads 56
   4. But the whole months are 119, one short of the 120 that the senior band starts at, so the stage is mature adult rather than senior

   This is the case that shows why the page reports a stage as well as an age. Rounded, this cat and the same cat one day later are both 56 in human years — nothing on the human-age row can tell them apart, and only the stage changes. It also pins the boundary the two sponsoring organisations disagree about: the AAFP's own chart puts senior at 10 and over, while the AAHA poster for the same guidelines has it starting at 11. This page follows the chart, since that is where the numbers come from.

Today is taken as the UTC calendar day, so in time zones ahead of UTC the age can be a day behind the date on your wall. The conversion is an approximation and the organisations that publish one do not agree: this page uses the AAFP's chart, which gives 56 human years at age 10, while Cornell gives 53 for the same cat. Neither is a measurement — they are rules of thumb fitted to how cats age on average. Under one year the figure is a straight line between two anchors rather than a reading from the chart, because the published charts list intermediate rows for the first year that do not fall on a line: a six-month-old cat is put at about 10 human years, where a straight line through 15 at twelve months gives about 8. The life stages follow the 2021 AAHA/AAFP guidelines, which define four age-related stages plus an end-of-life stage that can occur at any age; that fifth stage is not shown here because it is not defined by age, so a cat is never badged as being in it. The two organisations also disagree about where senior begins — the AAFP's chart says 10 and over, the AAHA poster says 11 — and this page follows the chart. And the page knows nothing about breed, whether the cat lives indoors or outdoors, or whether it has been neutered, all of which move how long a cat lives without moving the conversion.

How do I work out how old my cat is in human years?

Count the first year as 15 human years, the second as 9 more, and every year after that as 4. A cat of 4 is therefore about 32, and a cat of 11 is about 60. The page does this for you from the birth date and also reports the cat's real age in months and days, because months are what the life stage is actually decided by.

Is one cat year really seven human years?

No, and the two ends of a cat's life are exactly where it fails. It comes from dividing a human lifespan by a cat lifespan, which assumes a cat ages at the same steady rate throughout. Cats do not: the first year takes a cat to about 15 in human years rather than 7, and the years after the second add only about 4 each. Cornell's veterinary school states outright that the rule of seven is not accurate.

At what age is a cat a senior?

Ten, by the chart this page uses, which prints senior as 10 years and over. Be aware that the two organisations behind the guidelines do not quite agree: the AAFP's chart and its guideline summary both say 10 and older, while the AAHA poster for the same guidelines says senior starts at 11. It is a one-year difference either way, and the practical advice it triggers — a check-up every six months rather than every year — is recommended for cats over 10 in both readings.

What are the life stages of a cat?

The 2021 AAHA/AAFP guidelines define four age-related stages. A kitten runs from birth to one year, a young adult from 1 to 6, a mature adult from 7 to 10, and a senior from 10 onwards. They also name a fifth, end-of-life stage, which can begin at any age and so is not shown as a band on this page. The older six-stage scheme, which some cat charities still use, splits the same span into kitten, junior, adult, mature, senior and super senior.

Why do different websites give different human ages for the same cat?

Because two respectable sources publish different rules. The AAFP's client chart gives 15 for the first year, 24 by the second and 4 a year after that; Cornell gives 16, 21 and 4. The gap shows up in the middle: at age 10 the AAFP's figure is 56 human years and Cornell's is 53. This page uses the AAFP's chart, because the life stages it reports come from the same organisation's guidelines. Both are approximations rather than measurements, so treat any single figure as a rough guide.

• 2021 AAHA/AAFP Feline Life Stage Guidelines — American Association of Feline Practitioners
• Feline life stages client chart (cat years to human years) — American Association of Feline Practitioners
• Feline life stage poster — American Animal Hospital Association
• The special needs of the senior cat — Cornell Feline Health Center
• 2021 AAHA/AAFP Feline Life Stage Guidelines — summary — RCVS Knowledge