Dog Age Calculator
Convert dog years to human years the accurate way — by size, not the old "times 7" myth. Enter your dog's age and size to see their human-equivalent age and life stage.
Use decimals for puppies — e.g. 0.5 = 6 months
Chihuahua = small · Lab = large · Great Dane = giant
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You might also need:Puppy Weight Calculator·Cat Age Calculator
How dog age is really calculated
each year after: small +4 · medium +5 · large +6 · giant +7
Dogs mature extremely fast early on — a one-year-old dog is roughly a teenager — then the pace settles into a size-dependent rhythm. Size matters because big dogs genuinely age faster: it's the reason a 10-year-old Chihuahua is middle-aged while a 10-year-old Great Dane is very elderly.
Dog years to human years chart
| Dog age | Small | Medium | Large | Giant |
|---|---|---|---|---|
| 1 | 15 | 15 | 15 | 15 |
| 2 | 24 | 24 | 24 | 24 |
| 5 | 36 | 39 | 42 | 45 |
| 8 | 48 | 54 | 60 | 66 |
| 10 | 56 | 64 | 72 | 80 |
| 13 | 68 | 79 | 90 | 101 |
| 16 | 80 | 94 | 108 | — |
What each life stage means
- Puppy (0–1): rapid growth — see the puppy weight calculator for where they'll end up, and the puppy feeding calculator for portions.
- Adult: maintenance mode — right-size the food bowl with the dog food calculator.
- Senior: twice-yearly vet checks, joint support, and watch weight — metabolism slows before appetite does.
Frequently asked questions
How do you convert dog years to human years?+
The vet-standard method: the first year of a dog’s life equals about 15 human years, the second adds 9 (so a 2-year-old dog is ~24), and every year after that adds 4–7 depending on size — smaller dogs age slower, giant breeds faster. The old "multiply by 7" rule is a myth.
Why do small dogs live longer than big dogs?+
Large breeds age faster at the cellular level — a Great Dane is senior at 6–7, while a Chihuahua may not be senior until 11. Researchers believe rapid growth accelerates aging. That is why this calculator asks for your dog’s size.
How old is a 7-year-old dog in human years?+
Roughly 44–50 human years depending on size: about 44 for a small dog, 47 for a medium dog, 50 for a large dog, and up to 56 for a giant breed.
When is a dog considered a senior?+
Small breeds: around 11 years. Medium: 10. Large: 8. Giant breeds: 6–7. Senior status is when age-related checkups (bloodwork, joints, teeth) should become twice-yearly — worth discussing with your vet.
Is there a scientific formula for dog age?+
A 2020 UCSD study of DNA methylation proposed: human age = 16 × ln(dog age) + 31. It tracks cellular aging in Labradors specifically, and gives surprising results for young dogs (a 1-year-old = 31 human years). Our calculator uses the size-adjusted veterinary chart, which better reflects lifespan differences across breeds.