This is the formula my vet used.
A cat is fully grown at 1 year and can have kittens.
so they consider the first year to be 16 people years.
The second year, a cat matures a great deal and it’s considered to be 8 more people years, so 24. After that, based on health issues that cats develop just like people, and the ages that cats die, they consider it 1 cat year = 4 people years. So based on this formula, 33 year old cat would be 148. So it’s close to their number.
I use a similar formula for cat and dog age equivalents, though I think three years per year might be a little closer than four for adult ages. Anyway, my post was basically a joke concerning cats’ proverbial nine lives.
Has this been gnawing at you for almost six months? Some sort of hobby might help.