What is the purpose of a cat age conversion chart?

A cat age conversion chart shows the equivalent of a cat's age in human years. Because cats mature at a different rate than humans and have a shorter lifespan, a cat that is 6 years old is roughly equivalent in health to a 42-year-old human.

Although sources differ on the correct formula, one method to calculate a cat's age is to count 15 cat years for the first year, 10 cat years for the second and 4 cat years for each human year after that. This formula does not work in extreme cases, however. The record for cat longevity is 38 human years, equivalent to 169 in cat years, while the record for human lifespan is just 122.5 years.