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Dog age calculator

Dogs don't age at a steady seven human years per year. They grow up fast in their first two years, then age at a pace that depends on size: a giant breed is a senior years before a Chihuahua. Enter your dog's age or birthday and breed to see their age in human years, their life stage, and how the popular formulas compare.

Size

Not sure? We use medium.

How old is your pet?

Enter an age to see human years.

The default is the size-based vet chart. See how pet age is calculated.

Dog years to human years chart

Dog age in human years, by age. Small is 20 lb or less, Medium is 21–50 lb, Large is 51–100 lb, Giant is over 100 lb.
Dog ageSmallMediumLargeGiant
1 year15151512
2 years24242422
3 years28282831
4 years32323238
5 years36363645
6 years40424549
7 years44475056
8 years48515564
9 years52566171
10 years56606679
11 years60657286
12 years64697793
13 years687482100
14 years727888107
15 years768393114
16 years808799121
17 years8491105128
18 years8895111135
19 years9299117142
20 years96103123149

See the printable dog age chart

The default is the size-based vet chart. See how pet age is calculated.

Dog life stages

Life stageAge
PuppyBirth to 12 months (18 months for large and giant breeds)
Young adultUntil about 3 years old
Mature adultFrom 3 years until the last quarter of expected lifespan
SeniorThe last 25% of expected lifespan: about 6½ years for giant dogs up to about 10½ for small dogs

Under one year

Dog age by breed

FAQ

How do I convert dog years to human years?

Use a size-based chart. A dog's first year equals about 15 human years and its second about 9 more. After that, each year adds 4 to 9 human years depending on size, with bigger dogs aging faster. The calculator on this page does this for you, months included.

Is one dog year really seven human years?

No. The ×7 rule is a myth. It makes young dogs seem far younger than they are (a one-year-old dog is closer to 15 than 7) and makes old small dogs seem older than they are.

Why do big dogs age faster?

Large and giant breeds have shorter lifespans and reach old age sooner. Researchers think their fast growth as puppies plays a part, but the exact reason is still being studied.

When is a dog considered a senior?

Vets generally consider a dog senior in the last quarter of its expected lifespan: around 10½ years for small dogs, 9 for medium, 8 for large and 6½ for giant breeds.

What is the DNA formula for dog age?

A 2020 study from UC San Diego compared age-related DNA changes in Labrador Retrievers and people and proposed human age = 16 × ln(dog age) + 31. It suggests dogs age very quickly at first, but it was measured in one breed only.