Dog Age Calculator
How old is your dog in human years? Enter their age and size to find out — plus their life stage.
By size (classic chart)
34
human years
Research formula (2020 study)
53
human years
Life stage: Adult
Dog years to human years chart
The classic size-based chart gives a dog 15 human years in year one and 24 at age two, then adds a set number each year depending on size. The research formula is shown for comparison.
| Dog age | Small | Medium | Large | Giant | Research |
|---|---|---|---|---|---|
| 1 year | 15 | 15 | 15 | 15 | 31 |
| 2 years | 24 | 24 | 24 | 24 | 42 |
| 3 years | 28 | 29 | 30 | 31 | 49 |
| 5 years | 36 | 39 | 42 | 45 | 57 |
| 7 years | 44 | 49 | 54 | 59 | 62 |
| 10 years | 56 | 64 | 72 | 80 | 68 |
| 13 years | 68 | 79 | 90 | 101 | 72 |
| 15 years | 76 | 89 | 102 | 115 | 74 |
Caring for your dog at every age
Puppies need a series of vaccines in their first 16 weeks, adults need regular boosters and checkups, and seniors benefit from more frequent vet visits. Keeping dates handy makes all of it easier — especially when a boarder or groomer asks for proof of vaccines.
Frequently asked questions
Is one dog year really seven human years?
No. The 7-to-1 rule is a rough myth. Dogs mature much faster in their first two years, then age more slowly, and larger breeds age faster than small ones. That's why this calculator offers a size-based chart and a research formula.
How does the research-based formula work?
A 2020 study of Labrador retrievers compared DNA methylation patterns in dogs and humans and proposed human age ≈ 16 × ln(dog age) + 31. It works best as a general guide and doesn't account for breed size.
Why do big dogs age faster?
Giant and large breeds tend to have shorter lifespans, so their senior years arrive sooner. That's why each size category adds more human years per dog year after age two.
When is a dog a senior?
Roughly 10+ years for small dogs, 9 for medium, 7–8 for large and about 6 for giant breeds. Your vet may suggest more frequent checkups from that point.
More pet guides & tools
This is general information, not veterinary advice. Every pet is different — check with your vet.