Cat Age Calculator

1. Enter your cat's age in years. If your cat is less than a year old, enter 0 in the years field and use the months field.
2. Enter additional months. This is especially important for young cats since aging is very rapid in the first year. A 6-month-old kitten is already equivalent to a 7 or 8-year-old human child.
3. Read the human equivalent age. This is calculated using the AAFP standard conversion: 15 human years for the first cat year, 9 more for the second year, and 4 human years for each year after that.
4. Note the life stage. The color-coded life stage badge tells you where your cat stands: Kitten, Junior, Prime, Mature, Senior, or Geriatric. Each stage has different health monitoring needs.
5. Use the reference table. The table at the bottom shows human equivalents for key cat ages from 6 months through 20 years.

The American Association of Feline Practitioners (AAFP) provides the most widely accepted conversion formula for cat age to human age. Unlike dogs, cat aging rates do not vary significantly by size or breed.

Year 1:  15 human years  (cats mature very rapidly)
Year 2:  +9 human years  (total: 24 human years)
Year 3+: +4 human years per year

Formula after year 2:
Human Age = 24 + (cat years – 2) × 4

Worked examples:

5-year-old cat:  24 + (5 – 2) × 4 = 24 + 12 = 36 human years
10-year-old cat: 24 + (10 – 2) × 4 = 24 + 32 = 56 human years
15-year-old cat: 24 + (15 – 2) × 4 = 24 + 52 = 76 human years

For young cats under 1 year, each month equals about 1.25 human years in the first year (1 month = about 1.25 years). At 6 months, a kitten is roughly equivalent to a 7.5-year-old human child.

This conversion is an approximation based on comparing physiological milestones: puberty, peak physical condition, the onset of age-related diseases, and average lifespan. A cat's 1-year mark corresponds to human sexual maturity at 15 years. A cat's 2-year mark corresponds to full physical maturity at about 24 years. The rate then slows to 4 human years per cat year.