Is a 10-year-old cat really 70? No. Cats grow up very fast: by their first birthday they are about as mature as a 15-year-old person, and by two they are in their mid-twenties. After that they age about 4 human years per year, so the old “multiply by 7” rule is wrong at almost every age. Enter your cat’s age in years and months, or switch to Birthday and pick the date. A shelter’s age estimate works fine. You get the age in human years, the life stage, how the ×7 rule compares, and a cat age chart.
How it works: the calculator uses the cat age chart from the AAHA/AAFP Feline Life Stage Guidelines (2021) and International Cat Care. A cat’s first year equals about 15 human years, the second adds about 9 (24 at age 2), and every year after that adds about 4. Kitten months follow the same chart: 1 month ≈ 1 year, 3 months ≈ 4, 6 months ≈ 10, 7 months ≈ 12. Ages in between are filled in proportionally. Life stages follow the 2021 guidelines: kitten up to 1 year, young adult 1–6 years, mature adult 7–10 years, and senior over 10 years.