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Cat age in human years — converter and life stages

How many human years does your cat have? We show the current cat age converter, life stages from kitten to senior, and a step-by-step example.

Cats age differently from humans and differently from dogs. The first two years of a cat's life are a period of rapid development — a helpless kitten turns into a capable adult. After that the pace slows down and stabilises at around four human years per year. Thanks to this, the conversion is simpler than for dogs, where the result depends on breed size.

The standard cat age converter

The most commonly used model, recommended by veterinary organisations, looks like this:

  1. The cat's first year = 15 human years
  2. The second year adds 9 years (24 human years in total after two years)
  3. Each subsequent year = 4 human years

A cat's life stages

Veterinarians divide a cat's life into several phases worth knowing when planning care:

  • Kitten (0–6 months) — a period of intense growth and socialisation
  • Junior (6 months – 2 years) — reaching physical maturity
  • Adult (3–6 years) — in their prime, the equivalent of a 28–40-year-old human
  • Mature (7–10 years) — the start of a slowing metabolism
  • Senior (11–14 years) — requires more frequent check-ups
  • Geriatric (15+ years) — the equivalent of a human past the age of 76

Example: a cat aged 8 years

Let's work out the human age of an eight-year-old cat:

  • Years 1–2: 24 human years (base)
  • Years 3–8: six years at 4 = 24 years
  • Total: 24 + 24 = 48 human years

This means that an eight-year-old cat is roughly at the age of a mature, middle-aged human — a good moment to consider preventive screening of the kidneys and thyroid, which can be problematic in older cats.

Outdoor cat versus indoor cat

The actual pace of ageing is also affected by lifestyle. Outdoor cats are more exposed to injuries, infectious diseases and accidents, which is why they live statistically shorter lives. Indoor cats often reach 15–20 years, and record-holders pass the 20-year mark.

Note: the values given are approximate and do not replace an examination. This is not veterinary advice — when assessing the condition of an older cat, consult a veterinarian.

Convert your cat's age precisely: Cat age calculator →