Dog Age Calculator
Convert your dog's age to human years using a size-adjusted formula based on veterinary research — way more accurate than multiplying by 7.
Dog Age to Human Age Conversion Chart (Medium Breed)
| Dog Age | Small (<20 lbs) | Medium (20–50 lbs) | Large (>50 lbs) |
|---|---|---|---|
| 1 year | 15 | 15 | 15 |
| 2 years | 24 | 24 | 24 |
| 5 years | 36 | 39 | 42 |
| 8 years | 48 | 54 | 60 |
| 10 years | 56 | 64 | 72 |
| 12 years | 64 | 74 | 84 |
| 15 years | 76 | 89 | 102 |
Based on: Year 1 = 15, Year 2 = +9, Years 3+ = 4/5/6 per year for small/medium/large. Human years are approximate.
Frequently Asked Questions
Is the 7-year rule for dogs accurate?
No — the 7× rule is a myth and is significantly inaccurate. Dogs age much faster in their early years and more slowly later. A more accurate model: Year 1 = ~15 human years (dogs reach sexual maturity and near physical peak). Year 2 = ~9 more human years (24 total). Years 3+: small dogs age ~4 human years/year; medium dogs ~5; large dogs ~6. So a 2-year-old medium dog is about 24 in human terms, not 14. A 2019 UC San Diego study using DNA methylation patterns found that young dogs age much faster than the 7× rule suggests.
Why do small dogs live longer than large dogs?
Large dogs age faster and have shorter lifespans than small dogs — the opposite of most mammals (elephants live longer than mice). In dogs, larger size is associated with higher growth hormone levels, faster cell turnover, and higher rates of cancer. Average lifespans by size: Small dogs (<20 lbs): 12–16 years. Medium dogs (20–50 lbs): 10–14 years. Large dogs (50–90 lbs): 9–12 years. Giant breeds (>90 lbs, e.g. Great Dane, Irish Wolfhound): 6–10 years. The longest-lived dog on record was an Australian Cattle Dog named Bluey who lived to 29 years.
What are the life stages of a dog?
Dog life stages (approximate, medium breed): Puppy (0–6 months): Rapid development, socialization window. Junior (6 months–2 years): Adolescence, reaching sexual maturity. Adult (2–6 years): Physical and mental prime, peak health. Mature (6–9 years): Equivalent to middle age, may slow slightly. Senior (9–12 years): Aging signs appear, more veterinary attention needed. Geriatric (12+ years): Significant aging, end-of-life care considerations. Large breeds reach senior status earlier than small breeds.
How can I tell my dog's age if I don't know it?
A veterinarian can estimate a dog's age from physical exam: Teeth: Puppy teeth appear at 3–6 weeks; adult teeth by 6 months; tartar and wear increase with age. Eyes: Lens cloudiness (nuclear sclerosis) is common in dogs over 7. Coat: Graying around the muzzle typically begins around 5–7 years. Muscle mass and joint flexibility decline with age. For a more precise estimate, DNA tests (e.g., Embark) can now estimate age within 1–2 years using epigenetic clock methodology.