Free dog age calculator
How old is your dog, really?
Two quick questions and we'll translate their age into human years. No account needed.
Step 2 of 3
Tell us about your dog
Not a dog?
Their ageKnow the exact birthday? Pick it above and you'll get a countdown too.
How dog years really work
The old multiply-by-seven rule is a myth: dogs age very fast at first, then settle down. A dog's first year counts as about 15 human years, and by their second birthday they are roughly 24 in human terms, whatever their size.
From year three onward, size takes over. Small breeds add roughly 4 human years per dog year, medium breeds around 5, and large and giant breeds 6 or more. A 15-year-old small dog lands around 76 human years, while a giant breed the same age would be around 115. That is why the calculator asks how big your dog is.
Our numbers follow the size-banded chart used by the American Kennel Club and AAHA, in line with AVMA guidance. Between charted ages we interpolate, so a dog of 3 and a half gets a sensible in-between number rather than a rounded-down one.
Dog years to human years chart
| Dog age | Small | Medium | Large | Giant |
|---|---|---|---|---|
| 1 year | 15 | 15 | 15 | 15 |
| 2 years | 24 | 24 | 24 | 24 |
| 3 years | 28 | 28 | 29 | 31 |
| 5 years | 36 | 37 | 40 | 44 |
| 7 years | 44 | 47 | 50 | 58 |
| 10 years | 56 | 60 | 66 | 78 |
| 12 years | 64 | 69 | 77 | 93 |
| 15 years | 76 | 83 | 92 | 115 |
Small is under about 10 kg (20 lb), large is over about 25 kg (55 lb), and giant covers breeds like Great Danes.
Frequently asked questions
Why isn't my dog's human age just its age times seven?
The multiply-by-seven rule dates from the 1950s and is rejected by the AKC, the AVMA, and veterinary schools. Dogs age very fast in their first two years and more slowly afterwards, so a straight multiplier does not fit.
Why do a small dog and a big dog of the same age show different human ages?
Body size changes how dogs age. Larger breeds have shorter lifespans and reach old age sooner, so a large dog shows a higher human age than a small dog of the same age. That is why the calculator asks for your dog's size.
Why is a one-year-old dog already 15 in human years?
Dogs grow up fast. A one-year-old dog is roughly a teenager: fully grown, sexually mature, and full of energy. The first year packs in about 15 human years, and the second brings the total to about 24.
When does a dog become a senior?
It depends on size. Small dogs are usually considered senior around 11, medium dogs around 10, and large dogs around 8. Giant breeds get there even earlier. Larger dogs move through every life stage faster.
What about the DNA-based dog age formula?
A 2020 study in Cell Systems proposed a formula based on DNA methylation. It is rigorous, but it was derived from Labrador Retrievers only and runs 15 to 20 human years hotter than the clinical chart through young and middle age, so we stick with the veterinary size chart for the number we display.
Where do these numbers come from?
We follow the size-banded chart used by the AKC and AAHA, which matches AVMA guidance: 15 human years for year one, about 24 by year two, then a per-year rate that depends on breed size.
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