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Dog Age Calculator

Convert your dog's age to human years using breed size based life stage math, from puppy to senior.

Dog age

Enter your dog's age and size. Results update live.

Human equivalent age
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Enter your dog's age to convert.

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Why the old 7 year rule is wrong

Dogs mature much faster than humans in their first two years: the first year equals about 15 human years and the second about 9. After that, aging slows and depends on size, with small dogs aging about 4 human years per year and giant breeds about 6.

Why size matters so much

Large and giant breeds age faster and live shorter lives on average than small breeds. A 10 year old small dog is roughly 56 in human years, while a 10 year old giant breed is closer to 78, which is why the calculator asks for size.

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Dog Age Calc FAQs

How old is a 5 year old dog in human years?
About 37 for a medium dog: 24 for the first two years plus 3 years at 4.5 per year. Small dogs come out a little younger, large dogs a little older.
Is the 1 dog year equals 7 human years rule true?
No, it is a myth. Dogs age fast early and slower later, and size changes the rate. The two stage math in this calculator matches veterinary guidance much better.
When is a dog considered a senior?
Around 7 years for large breeds and 10 or more for small breeds. Senior dogs benefit from twice yearly vet checks and joint friendly exercise.
Do mixed breeds age differently?
Use the adult weight to pick the size category. Mixed breed aging follows size more closely than breed, so weight is the best guide.
Why do small dogs live longer?
Smaller dogs tend to age more slowly after maturity and develop fewer age related diseases early. Genetics, weight management and dental care also play big roles.
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