How dog years really work
Dogs pack a lot of growing up into their first two years — roughly 15 human years in year one, reaching about 24 by the end of year two. After that, ageing slows and depends on size: small dogs add about four human years per dog year, while giant breeds add closer to seven. That’s why two dogs the same age can be very different “ages” in human terms.
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 | 29 | 30 | 31 |
| 5 years | 36 | 39 | 42 | 45 |
| 7 years | 44 | 49 | 54 | 59 |
| 10 years | 56 | 64 | 72 | 80 |
| 13 years | 68 | 79 | 90 | 101 |
| 16 years | 80 | 94 | 108 | 122 |
Human-year equivalents are approximate and vary by breed and health.
Knowing your dog’s life stage helps you care for them better — a senior dog needs different food, exercise, and vet checks than a young adult. New to it all? Our new puppy checklist and dog safety checker are good places to start.
Frequently asked questions
Is one dog year equal to seven human years?
No — the “×7” rule is a myth. Dogs mature fastest in their first two years (roughly 15 human years in year one, and about 24 by year two), then age more gradually. How fast they age after that depends on their size, with larger dogs ageing faster than small ones.
Why does size change my dog’s age in human years?
Smaller dogs tend to live longer and age more slowly in later life, while giant breeds age faster and have shorter lifespans. That’s why a size-aware calculator gives a more realistic number than a single formula for all dogs.
When is a dog considered a senior?
It varies by size: giant breeds can be seniors by 6, large breeds around 7, and small breeds closer to 9–10. Your vet can tell you what to watch for as your dog enters their senior years.