Cat Age Calculator

Convert cat years to human years

This cat age calculator converts a cat’s age into human years, and it can also convert human years back into cat years. The result includes a life stage, so you can see whether the age falls in the kitten, young adult, mature adult, or senior range. If you are asking how old is my cat in human years, start with the cat’s age in years and months.

How the cat years calculation works

A cat does not age at a flat “seven human years per cat year.” The first months move quickly, then the rate slows. This cat years calculator uses four bands:

• Up to 6 months: human years = 20 × cat years
• From 6 months to 1 year: human years = 10 + (cat years − 0.5) × 10
• From 1 year to 2 years: human years = 15 + (cat years − 1) × 9
• After 2 years: human years = 24 + 4 × (cat years − 2)

Those bands land on the usual cat year chart: 6 months is 10 human years, 1 cat year is 15, 2 cat years are 24, and each later cat year adds 4 human years. The human-years result is rounded to the nearest year. The reverse conversion uses the same bands and shows cat years to one decimal place.

What your cat age in human years includes

• Cat years to human years, rounded to the nearest human year
• A life stage based on the cat’s age: kitten, young adult, mature adult, or senior
• The reverse result when you enter human years instead

Cat life stages

The life stage follows the 2021 AAHA/AAFP feline life stage guidelines and uses the cat’s age, not the rounded human-year number.

• Kitten: birth up to 1 year
• Young adult: 1 year through 6 years
• Mature adult: 7 to 10 years
• Senior: over 10 years

A 6-month-old kitten is about 10 human years. A 1-year-old cat is a young adult, at about 15 human years. The guidelines also name an end-of-life stage that can happen at any age, so this calculator does not assign that stage from age alone.

Cat years chart

Why this cat age in human years is an estimate

The chart describes a typical cat. Indoor and outdoor life, breed, diet, and medical care all change how an individual cat ages. Use the result as a cat years to human years comparison, not as a veterinary diagnosis. Teeth, eyes, and coat are still the practical clues when a cat’s birth date is unknown.