Dog Age Calculator
Convert dog years to human years by size class (AVMA formula), with reverse mode and a full age chart.
Dog Years to Human Years Chart
| Dog’s age | Small | Medium | Large |
|---|---|---|---|
| 6 months | 7.5 yrs | 7.5 yrs | 7.5 yrs |
| 1 yr | 15 yrs | 15 yrs | 15 yrs |
| 2 yrs | 24 yrs | 24 yrs | 24 yrs |
| 3 yrs | 28 yrs | 29 yrs | 30 yrs |
| 4 yrs | 32 yrs | 34 yrs | 36 yrs |
| 5 yrs | 36 yrs | 39 yrs | 42 yrs |
| 6 yrs | 40 yrs | 44 yrs | 48 yrs |
| 7 yrs | 44 yrs | 49 yrs | 54 yrs |
| 8 yrs | 48 yrs | 54 yrs | 60 yrs |
| 9 yrs | 52 yrs | 59 yrs | 66 yrs |
| 10 yrs | 56 yrs | 64 yrs | 72 yrs |
| 12 yrs | 64 yrs | 74 yrs | 84 yrs |
| 14 yrs | 72 yrs | 84 yrs | 96 yrs |
| 16 yrs | 80 yrs | 94 yrs | 108 yrs |
Chart uses the AVMA size-class convention above. The old “7 dog years per human year” rule of thumb is a myth — it badly undercounts puppy and senior years.
Quick Answer
Dogs age fastest early in life, so the old 7-to-1 rule is wrong. The AVMA convention counts a dog’s first year as about 15 human years, the second as about 9 more (24 total), and each later year as 4 human years for small dogs, 5 for medium, 6 for large — bigger dogs age faster. Enter an age and size above, convert in reverse, or see the full chart.
How It Works
Choose the direction: dog → human or the reverse human → dog
Select your dog’s size class: small, medium, or large
Enter the age in years (and months for puppies)
Read the converted age and the formula used, with the AVMA source
Check the chart below for the full age-by-size table
Key Facts
- First dog year ≈ 15 human years; second year adds ≈ 9 (→ 24)
- After age 2: +4 human years for small, +5 medium, +6 large dogs
- Formula labeled with source: AVMA (American Veterinary Medical Association)
- Reverse mode: convert a human age into an equivalent dog age
- Months supported, not just whole years
- Full chart covers ages from 6 months to 16 years across three size classes
- 100% client-side — free, no sign-up, nothing uploaded
Frequently Asked Questions
How do I calculate my dog’s age in human years?
Use the AVMA size-class convention: the first year equals about 15 human years, the second year adds about 9 more (so a 2-year-old dog ≈ 24 human years), and every year after that adds roughly 4 human years for a small dog, 5 for medium, or 6 for large. A 4-year-old medium dog is about 24 + 2×5 = 34 human years old. The calculator above does this instantly.
Is the “multiply by 7” dog years rule accurate?
No — it’s a myth from mid-20th-century marketing that simply divided the human lifespan (~70) by the dog lifespan (~10). It badly undercounts young dogs (a 1-year-old dog can reproduce and is physiologically closer to a 15-year-old human) and overcounts seniors. Modern guidance counts the first two years much faster, then slows down.
Why do larger dogs age faster?
Counterintuitively, big dogs have shorter lives: a Great Dane may live 7–10 years while a Chihuahua often reaches 15+. Large breeds grow extremely quickly as puppies, which appears to accelerate aging — higher levels of the growth hormone IGF-1 are linked to both large size and shorter lifespan. That’s why the per-year multiplier grows with size class.
How old is a puppy in human years?
A 6-month-old puppy is roughly 7–8 human years old (puppyhood flies by), and a 1-year-old dog is about 15. By 18 months a dog is around 19–20 in human terms — physically an adolescent. Use the months field above to convert puppy ages precisely.
What is the UCSD 2019 dog-age formula?
A 2019 University of California San Diego study of Labrador retrievers used DNA methylation (the epigenetic clock) to derive human_age = 16 × ln(dog_age) + 31. It matches the early fast-aging pattern well — a 1-year-old lab maps to about 31 — but it was built from one breed and doesn’t separate size classes, so the AVMA size-class convention remains the everyday standard for mixed-age, mixed-breed dogs.