The veterinary mapping
The AAHA / AAFP feline life-stage guidelines use a piecewise mapping that reflects how rapidly cats mature in their first two years and then settle into a steadier ageing pace:
- Year 1: equivalent to ~15 human years
- Year 2: +9 human years (so age 2 cat ≈ 24 human)
- Each subsequent cat year: +4 human years
By that table, a 5-year-old cat is roughly 36 human years; a 10-year-old cat is roughly 56; a 15-year-old cat is roughly 76.
Indoor vs outdoor
The single biggest factor shaping cat lifespan in Canada is whether they go outdoors. Indoor cats avoid traffic, predators, fights and most infectious diseases; outdoor cats are exposed to all of those, especially in suburban and rural areas. Spaying or neutering also significantly extends median lifespan.
What this tool isn’t
This is a friendly comparison, not a clinical reading. If your cat seems to be ageing rapidly, has changes in coat, weight, appetite, litter habits, or activity, talk to your veterinarian rather than rely on a number on a webpage.