Scientific Dog Age Calculator
Forget the "times 7" myth. Use the new scientific formula.
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What this calculator does
This calculator converts your dog's age into an equivalent human age using a formula from a 2020 study of how DNA changes as dogs grow older. Pick a breed, enter your dog's age in years and months, and you'll get the human-equivalent age, a life stage (puppy, adult, senior or geriatric), and the typical life expectancy for that breed's size.
How to use it
- Start typing your dog's breed and pick it from the list. For a mixed breed, choose the mixed-breed option that matches your dog's adult size.
- Enter the age in years, and months if you know them.
- Select Calculate Human Age.
Why "times 7" is wrong
The old rule says one dog year equals seven human years. It's easy to remember but doesn't match how dogs actually age. Dogs grow up very fast: a one-year-old dog is physically closer to a young adult than to a seven-year-old child. After that, aging slows down. The "times 7" rule underestimates young dogs and overestimates old ones.
The formula
In 2020, researchers at the University of California San Diego tracked chemical marks on DNA (methylation) that change in a predictable way with age. Comparing those marks in dogs and humans, they found this relationship:
human age = 16 × ln(dog age) + 31
"ln" is the natural logarithm, which rises steeply at first and then levels off, just as dog aging does.
Worked examples
| Dog's age | Formula result | "Times 7" rule |
|---|---|---|
| 6 months | about 20 | 3.5 |
| 1 year | 31 | 7 |
| 2 years | about 42 | 14 |
| 4 years | about 53 | 28 |
| 10 years | about 68 | 70 |
The formula's biggest differences show up in the first few years: by age 2, a dog has already reached the human equivalent of its early 40s.
What about breed and size?
The study's dogs were all Labrador Retrievers, a large breed. Size matters a lot for lifespan: small dogs often live into their mid-teens, while giant breeds may live 7 to 10 years. Researchers haven't yet published a version of the formula for each breed, so this calculator uses the study's formula for every dog and shows the typical life expectancy for your breed's size alongside the result. For small breeds, treat the result as slightly high in the senior years; for giant breeds, slightly low.
Frequently asked questions
Is this accurate for my dog?
It's a well-grounded estimate, not a medical assessment. Individual dogs vary with genetics, weight, diet and health. Your vet can give a better picture of your dog's condition.
When is my dog a senior?
This calculator follows the American Animal Hospital Association's 2019 Canine Life Stage Guidelines: a dog is a senior in the last 25% of its expected lifespan, and geriatric once it reaches its life expectancy. That's why a 7-year-old Great Dane counts as a senior while a Chihuahua isn't one until about 12.
Why doesn't my breed appear?
The list covers about 270 breeds, plus four mixed-breed options by adult weight. For an unlisted breed, choose the mixed-breed option that matches your dog's size.
Does the formula work for puppies?
It works from about 2 months old. Very young puppies develop so quickly that any human comparison is rough.
Can I use this for cats?
No. Cats age on a different curve, and this formula was developed for dogs only.
Sources: Wang T, Ma J, Hogan AN, et al. Quantitative Translation of Dog-to-Human Aging by Conserved Remodeling of the DNA Methylome. Cell Systems, 2020;11(2):176-185. Life stages: AAHA 2019 Canine Life Stage Guidelines. Formula as reported by BBC Science Focus, July 3, 2020. Last reviewed on SuiteWebTools: October 2026.