Cat Age Calculator

A 1-year-old cat is 15 in human years, and a 10-year-old is 56

A cat grows up as much in its first 2 years as a person does in 24, and after that each year counts as about 4 human years. This is the conversion chart published by the UK charity International Cat Care (iCatCare). The table in a Japanese Ministry of the Environment pamphlet (the column for small and medium dogs and cats) gives the same values: 15 at age 1, 24 at age 2 and 84 at age 17. By this chart a 5-year-old cat is 36 in human years, a 10-year-old is 56, a 15-year-old is 76 and a 20-year-old is 96.

Enter an age or a birthday in the calculator above and it converts it with this chart. It also shows the life stage from the 2021 AAHA/AAFP guidelines, the time left until the next stage, and the remaining life expectancy read from a life table built from UK veterinary records. The two-sided ruler shows how cat age and human age line up, and you can click or drag it to see any other age at once.

Why convert to human years

Cats tend to hide illness and discomfort. The 2021 AAHA/AAFP guidelines point out that signs of illness and pain are often hard to detect in cats and that cats are seen as self-sufficient, so they go to the vet less often than dogs. In a 2006 figure the guidelines cite, dogs made 2.3 veterinary visits a year and cats 1.1. Turning an age into human years and a life stage makes it easier to see what needs attention now.

• Choosing how often to have a check-up: the guidelines advise an exam at least once a year for every cat and at least every 6 months for seniors (over 10 years). An 11-year-old cat is 60 in human years, which is the point to shorten the interval.
• Matching care to the stage: the guidelines give examples for each stage: checking kittens for congenital defects, preventing obesity in young adults, and finding kidney disease early in mature adult and senior cats.
• Placing a cat you have taken in: if a shelter or breeder estimates a cat at 3 years, that is 28 in human years, and at 7 years it is 44. Both are adults, but what to look after next is different.
• Explaining it to the family: a stage name and a human age help when you tell a child that the cat is already an old lady. It is worth adding that this is an average conversion.

How it is calculated

1. Human age: the points of the iCatCare chart are used. 1 month is 1, 2 months 2, 3 months 4, 4 months 6, 5 months 8, 6 months 10, 7 months 12, 12 months 15, 18 months 21 and 2 years 24. After 2 years, each year adds 4 (a third of a year for each month).
2. Months between chart points: values are interpolated in a straight line between the neighboring points. 9 months lies two fifths of the way from 7 months (12) to 12 months (15), so 12 + 3 × 2 ÷ 5 = 13.2, which rounds to 13. For 10 years 6 months, 56 + 2 = 58.
3. Above 25 years: the iCatCare chart ends at 25 years (116). Older ages are extended at the same rate (1 year = 4) and labelled as an estimate. The calculator stops at 38 years, the Guinness record (38 years 3 days).
4. Life stage: the four stages of the 2021 AAHA/AAFP guidelines are used: kitten (birth up to 1 year), young adult (1-6 years), mature adult (7-10 years) and senior (over 10 years). The ranges are read in completed years, so up to 10 years 11 months is shown as mature adult and senior starts at 11. The six iCatCare stages are shown as well.
5. Remaining life expectancy: it is read from the life table that a UK VetCompass study (published 2024) built from 7,936 cats that died under primary veterinary care in 2019. If you choose a sex, the female or male table is used, and months between ages are interpolated between the neighboring years. The table gives age 20 and over as a single group, so there is no value for each age from 20.
6. Share that reached 20: among the cats in the same life table that reached the current age (in completed years), the proportion that went on to reach 20 or more. At age 10 it is 332 of 5,125 cats, or 6.5%.
7. Entering a birthday: the age is counted in completed months up to today (a month is not counted until its day arrives). For a birthday on 29 February, 1 March is treated as the birthday in non-leap years.

Cat age to human age chart

Human age is the iCatCare chart value. Remaining life expectancy is from the UK VetCompass 2019 life table (both sexes). From age 20 the table gives one group with no value for each age (the average for the 20+ group is 1.32 years).

How long do cats live? Surveys disagree

The two surveys differ by about 4 years because they are built differently. The UK life table comes from veterinary records of cats that died, so cats that died young from accidents or illness are included in the average. The Japanese data come from a questionnaire on dog and cat keeping. In the Japanese survey, cats that never go outside lived 2.1 years longer on average than cats that do (16.34 against 14.24 years).

In the UK study, females lived 1.33 years longer than males, and purebred cats 1.48 years less than crossbred cats. Entire (non-neutered) cats had 4.29 times the odds of dying before age 3. Among cats that died after 9 months of age, neutered cats lived 1.07 years longer in a model adjusting for sex, breed status and body weight.

Life expectancy at birth by breed (UK)

The study lists only breeds with at least 15 recorded deaths. Breeds with few deaths have wide confidence intervals, so their ranking should not be taken as settled. Breed shows up only in the lifespan data. No source supports changing the human-age conversion by breed, so the calculator uses the same chart for every cat.

AAHA/AAFP stages and iCatCare stages

The AAHA/AAFP guidelines list what to look after at each stage. For kittens the main points are the initial vaccines and the booster at 6 months of age, socialization, getting used to handling and the carrier, and checking for congenital defects. Young adulthood is the time to keep weight from creeping up and to check the mouth for gum disease and tooth resorption. For mature adult and senior cats the focus is on finding kidney disease early and on watching for changes in weight, appetite, water intake, crying at night and movement. The guidelines add that the age bands are a starting point that differs from cat to cat, and that a healthy cat over 10 may be managed as a mature adult at the veterinarian's discretion.

Common mistakes

• Multiplying the age by 7: counting a 1-year-old as 7 gives less than half of the chart value (15), and counting a 15-year-old as 105 gives 29 more than the chart (76). Cats grow fast in the first 2 years and age more slowly afterwards.
• Changing the human age by breed or indoor living: no source could be found for correction formulas that raise or lower the human age by breed or living conditions. Differences by breed and living conditions are seen in lifespan data, while human age is read from the same chart.
• Applying life expectancy at birth to the current age: the UK life expectancy of 11.74 years at birth is an average that includes cats that died young. It does not mean a 12-year-old cat is past its average lifespan. In the same life table, 12-year-old cats lived another 4.24 years on average.
• Treating the start of the senior stage as one fixed age: the guidelines' table gives mature adult as 7-10 years and senior as over 10 years, while the text also mentions "senior cats aged 10 years and older". This calculator reads completed years and shows senior from 11, but it is a good idea to discuss the check-up interval with your vet once the cat turns 10.
• Entering the adoption day as the birthday: if the cat was already several months old when you took it in, add those months. If you do not know the birthday, use "By age" and add the age at adoption to the time you have had the cat.

Limits and cautions

• Human age is an average conversion from the iCatCare chart. At the same age, ageing differs with health and living conditions, and the Japanese Ministry of the Environment table also says values differ by breed and living environment.
• Remaining life expectancy and the share that reached 20 are averages from UK veterinary records. They may differ for cats where you live and do not predict the lifespan of a single cat. Conditions other than sex (breed, neutering, indoor living) are not included in these values.
• As the guidelines state, the age bands for life stages are not fixed lines but a starting point for care.
• If you are worried about your cat's health, see a vet before relying on the result. The items for each stage summarize the guidelines, and the vaccine types and intervals are for your vet to decide.
• Your input is calculated only in this browser and is not sent to a server.

Sources

• 01International Cat Care: How to tell your cat's age in human yearsChart (1 month = 1 to 25 years = 116), first 2 years = 24 human years and 4 per year after that, six stages (Kitten, Junior, Adult, Mature, Senior, Super Senior). Checked 2026-10-22
• 02Japan Ministry of the Environment pamphlet, 「犬と猫の年齢換算表」Column for small and medium dogs and cats: 15 at age 1, 24 at age 2, then 4 per year (84 at age 17); values differ by breed and living environment
• 03Quimby J et al., 2021 AAHA/AAFP Feline Life Stage Guidelines, J Feline Med Surg 23(3):211–233Four stages (kitten birth to 1 year, young adult 1-6, mature adult 7-10, senior over 10), exams at least yearly and for seniors at least every 6 months, per-stage items in Table 2
• 04Teng KT et al. (2024), Life tables of annual life expectancy and risk factors for mortality in cats in the UK, J Feline Med Surg 26(5)VetCompass 2019 life tables (all, female, male, crossbred, purebred), life expectancy at birth 11.74 years, breeds in Table 6, neutering and breed-status risks in Tables 7 and 8
• 05Japan Pet Food Association, 「令和6年 全国犬猫飼育実態調査」Average cat lifespan 15.92 years, cats that never go outside 16.34, cats that go outside 14.24 (p. 27)
• 06Guinness World Records: Oldest cat everCreme Puff (Austin, Texas, USA), born 3 Aug 1967, died 6 Aug 2005, 38 years 3 days

Frequently asked questions

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