Read against UK life tables for cats and for people, the usual cat-years chart sets the average cat's lifespan 17 to 19 human years short of a person's, on our arithmetic. The chart gives a cat 15 human years for its first year and 24 by its second birthday, then adds 4 a year. No veterinary chart we opened uses the familiar seven to one. The earliest copy of this one we could open, in 2010 guidelines from two US veterinary associations, states no basis for its numbers, and the 2021 guidelines that replaced them print no human-age column.
The cats in that comparison are UK cats under veterinary care, from a 2024 life table covering cats on practice records in 2019. Their average life expectancy at birth, 12.5 years for females and 11.2 for males, reads on the chart as 66 and 61. UK women and men in the national tables for 2017 to 2019 could expect 83.1 and 79.4 years. Singapore residents' figure for 2024, 83.7, sits above both, so a Singapore comparison would widen the gap. We found no life table for cats in Singapore or Malaysia.
The earliest copy of the chart we could open lives in a 2010 guideline
The 2010 AAFP-AAHA Feline Life Stage Guidelines, from the American Association of Feline Practitioners and the American Animal Hospital Association, print the chart in a box on page 71. A 6-month-old is 10, a 1-year-old 15 and a 2-year-old 24. Each year after adds 4, up to the last row: 25 years, at 116.
The text credits its six life stages to a classification "developed by the Feline Advisory Bureau", a UK charity, and thanks the charity's WellCat for Life programme "in helping to formulate the guidance". Nothing says how the human column was worked out: no study, data or method. The guidelines cite a 2008 WellCat handbook for vets that is not online, so whether the column appeared there first we could not establish. The seven-to-one rule appears in none of the six veterinary sources we read, and we could not trace where it started.
A human-years column survived after the 2021 guidelines left it out
The 2021 AAHA/AAFP Feline Life Stage Guidelines cut the stages from six to four, plus an end-of-life stage. Their Table 1 gives ages for each stage and nothing else, and the word "human" turns up only in phrases such as the bond between people and cats. The text does not say why the conversion went.
It lives on elsewhere. International Cat Care, which its history page says was "Initially called the Feline Advisory Bureau (FAB)", publishes the same figures in an article updated on 28 November 2025. A 2019 Zoetis poster on AAHA's website prints it under the heading "My pet's physiological age", citing 2010. Pages ranking for the question in English and Chinese usually credit the chart to AAHA, AAFP and International Cat Care, with no year.
Kittens grow up mostly before seven months on both charts
Both charts are front-loaded. A kitten of 6 months is 10 and one of 7 months is 12, so the last five months of the first year add only 3. For the first four months the 2010 box gives ranges, such as 2 to 4 human years at three months. International Cat Care gives single figures, 4 at three months, and wherever both charts have a row, its figure sits inside the 2010 range. The two differ in precision rather than substance, and from two years on they match row for row.
Until 12 October 2026 our cat age calculator multiplied the first year by 15, a straight line that ran low through kittenhood: at 7 months it gave 8.75 against the charts' 12. It also read a blank age as five years, had no upper limit, mixed 2010 and 2021 stage names, and credited the chart to the 2021 guidelines. The revised calculator reads International Cat Care's rows, joins neighbouring rows with a straight line and labels those readings "about", shows the 2010 range beside it up to four months, and refuses a blank age or one past 25. On its reading a 9-month-old is about 13.
UK men and women outlive the average cat by nearly two decades on the chart's scale
In the life table Teng and colleagues published in 2024, built from the records of 7,936 cats in primary-care practices, half the cats are still alive at about 12.8 years on our interpolation. O'Neill and colleagues' 2015 study of about 4,000 cats in English practices gives a median longevity of 14.0 years, the age that half fall short of and half pass. On the chart those medians become 67 and 72.
Our lead comparison matches country, years and sex, average against average. The chart turns female cats' 12.51 years into 66.0 and males' 11.18 into 60.7. The Office for National Statistics gives UK women 83.1 years and men 79.4 for 2017 to 2019, leaving gaps of 17.1 and 18.7 years by our arithmetic.
Read backwards, the chart puts Singapore residents' 83.7 years at a cat of 16.9. About one in five cats in Teng's table are still alive at that age, while 60% of residents reach 83.7 in SingStat's 2024 life table. That is a mixed measure, an average set beside survival shares. SingStat's 2025 figure, 83.9, is marked preliminary, so we used the complete 2024 table.
Teng's table is a hypothetical cohort built from deaths recorded between January 2019 and March 2021, and its authors say it underestimates first-year risk. Matching survival is only one way to define "equivalent". The chart is not a survival map, and no source we opened says what it measures. The 2009 AAFP Senior Care Guidelines pair a single trait instead: half of cats and half of humans show "signs of cognitive dysfunction (dementia)" by 15 and 85 respectively, citing earlier papers. The chart puts a 15-year-old cat at 76. That is one trait at one age, and no conversion.
Cats age into the senior stage after ten under the current guidelines
The 2021 guidelines define a kitten as birth up to 1 year, a young adult as 1 through 6, a mature adult as 7 to 10 and a senior as "aged over 10 years". The end-of-life stage "can occur at any age", and there is no longer a geriatric stage. The AAFP's 2021 Senior Care Guidelines add that some cats may be called senior "as early as 8 years of age". International Cat Care still uses six stages, with senior at 11 to 14 and super senior from 15.
The two 2021 documents do not give the same testing interval for cats of 7 to 10. The Life Stage guidelines' Table 4 lists "Every 1–2 years" for mature adults and "At least yearly" for seniors, a footnote calling these the Task Force's opinion for apparently healthy cats. The Senior Care guidelines suggest baseline tests "at least annually, starting at age 7-10 years". Of its own stages, the 2021 Task Force wrote that "any age groupings are inevitably arbitrary demarcations along a spectrum and not absolutes."
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