How Old Is My Dog? Dog Years by Birth Date

“How old is my dog” by date of birth is a two-step question: first find your dog’s exact age from their birth date, then convert those years into human-equivalent years.

Forget “multiply by seven”

The old rule that one dog year equals seven human years is a myth. Dogs mature very fast in their first two years, then age more slowly, so a flat multiplier is inaccurate.

The modern dog-age formula

A widely cited 2019 study suggests a better estimate: human age ≈ 16 × ln(dog’s age in years) + 31. In practice that means a 1-year-old dog is roughly a 31-year-old human, and ageing slows from there.

Size matters too

Breed size changes the picture: small dogs generally live longer and age more gently, while large and giant breeds age faster in later life. Vet charts adjust the human-equivalent age by weight class for this reason.

How to work it out

Enter your dog’s date of birth into an age calculator to get their exact age in years and months, then apply the formula or a size-based chart to estimate their age in human years.

Get your dog’s exact age first

Enter your dog’s date of birth to find their exact age, then convert to human years.