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A guide based on standard veterinary charts; indoor cats commonly reach their late teens, and the record is 38.
What The Cat Age Calculator Works Out
- Human age equivalent: the first cat year counts as 15 human years and the second as 9 (so a 2-year-old is about 24), then each further year adds 4. That makes a 5-year-old about 36, a 10-year-old about 56 and a 16-year-old about 80.
- Life stage: the standard veterinary stages: kitten (to 1), junior (1 to 2), adult (3 to 6), mature (7 to 10), senior (11 to 14) and super senior (15 plus). Care changes with the stage: mature and senior cats benefit from weight monitoring and blood pressure checks, since kidney disease and hyperthyroidism are common and manageable when caught early.
- Chart table: the standard formula for cats aged 1 to 21, for quick reference.
- Lifestyle (advanced): sets the typical lifespan used by the lifespan card. Indoor cats routinely live into their late teens (typical 16), cats with outdoor access somewhat less (14), and mostly-outdoor cats less again (11) because of traffic, fights and disease.
- Extra months (advanced): adds months to the whole years so a cat of 5 years 8 months is aged as 5.67 years.
- Human years per cat year (advanced): the rate applied after age 2. The standard chart uses 4; some vets use 5 for outdoor cats or 3 for very long-lived indoor cats.
- Share of typical lifespan (advanced): the cat's age as a percentage of the lifestyle's typical lifespan, or a lifespan you enter. Ticking neutered adds about 1.5 years, in line with UK data showing neutered cats live longer on average. Averages only: the record is 38.
- Human age at next birthday (advanced): how many human years the next cat year adds, so you can see how quickly a mature cat moves through the senior stages.
- Vet check-ups (advanced): annual for adults, twice-yearly from age 7 and frequent visits for kittens; the card works out when the next is due from the months since the last one.
- Senior from (advanced): how long until the cat reaches the senior stage at 11, when UK vets recommend more frequent checks.
- Milestone table (advanced): the cat age at which this cat reaches each human milestone (21, 30, 40 and so on up to 100) and how far away each is. A guide rather than a diagnosis; your vet's assessment of your individual cat is what counts.
Source and further reading: PDSA pet health advice.