The timeworn cat age formula no longer holds true, writes Elizabeth Vecsi. A cat celebrating his first birthday is actually the equivalent of a person who is 15 years old, a 10-year-old cat is the equivalent of 56 and a 17-year-old cat is the equivalent of 84.
Source: Catnip, April 26, 2019. Link. New Feline Life Stages Guidelines developed jointly by the AAFP and AAHA include a new cat age calculator. It was developed to outline life stage wellness programs in order to aid the veterinary community in delivering the most comprehensive care for cats.