First year
Dogs and cats are treated as about 15 human years at age 1.
Pet Age Calculator
Convert your dog or cat's age to human years. Uses size-based formulas for small, medium, and large dog breeds.
Pet Age Converter
Species Lifecycle Bridge
Convert your pet's age to human years to understand their life stage.
Equivalent Human Age
29
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Pet aging is fastest in the first two years, then varies by species and size
This calculator converts dog or cat age into a human-age equivalent to make life stage easier to understand. Cats use 15 human years for year one, 24 by year two, then 4 per year; dogs add 4, 5, or 6 human years per year after age two depending on size.
Conversion rules
Second year
Age 2 converts to about 24 human years.
After that
Cats +4/year; small dogs +4, medium +5, large +6/year.
How to use
- Choose dog or cat.
- Enter your pet's actual age.
- For dogs, select small, medium, or large size to see the human-age equivalent.
Frequently asked questions
Is one dog year really seven human years?
That rule is too simple. The first two years mature faster, and later aging differs by body size.
Why do large dogs age faster?
Large dogs often have faster adult aging and shorter average lifespans, so the calculator uses a larger yearly factor.
Can this set my pet's checkup schedule?
It can suggest a rough life stage, but breed, weight, and medical history should guide veterinary care.
Results are general conversion estimates and are not a substitute for professional veterinary advice or care.