How old is your dog in human years? The answer depends on size.
Enter your dog's age and size (or pick a breed) and this calculator converts it using two real veterinary methods side by side: the AVMA size-adjusted guideline and the UCSD epigenetic clock. Small breeds age slower; giant breeds age faster. The old "multiply by 7" rule is a myth - see the real numbers below.
Results
Everything runs locally - nothing is uploaded.
How to use this dog age calculator
Type the dog's age in years and any extra months (0-11). For a puppy under one year, enter 0 years and the months, for example 6 months = 0 years + 6 months.
Pick small, medium, large or giant, or select a breed from the list and the size is set automatically. Size is the single biggest factor in how fast a dog ages.
Results show the human-age equivalent from the AVMA size-adjusted guideline, the UCSD epigenetic clock, the life stage (puppy to geriatric), the expected lifespan for that size, and a full dog-years-to-human-years chart.
Frequently Asked Questions
How many dog years are in a human year?
There is no single multiplier. The AVMA guideline says a dog's first year equals about 15 human years, the second year adds about 9 more (24 total), and after that small dogs age about 4 human years per dog year, medium dogs 5, large dogs 6 and giant dogs 7. The old "1 dog year = 7 human years" rule is a myth.
What is the most accurate dog age formula?
The most cited scientific formula is the UCSD epigenetic clock: human age = 16 x ln(dog age) + 31. It was published in Cell Systems (Wang et al., 2020) after studying DNA methylation in Labrador Retrievers. It applies to dogs roughly one year and older; for puppies the veterinary 15-24 size-adjusted guideline is more practical.
Do small dogs age slower than large dogs?
Yes. Small breeds generally live longer and age more slowly after maturity, while large and giant breeds age faster and are considered senior earlier. A Great Dane is senior around 6 years, while a Chihuahua may not be senior until 9-11.
How do I know if my dog is a senior?
Veterinarians classify dogs by size: giant breeds are senior around 6, large breeds around 7, medium breeds around 8, and small breeds around 9-10 years. A dog is usually considered geriatric two years after reaching senior status.
Is the 7 dog years rule accurate?
No. The "1 dog year = 7 human years" rule is an outdated myth that ignores the fast puppy growth in the first two years and the large differences between small and giant breeds. Real dog aging is non-linear and size-dependent.
How is a puppy's age calculated in human years?
Puppies mature very fast. A common veterinary table: 1 month about 1 human year, 2 months about 3, 3 months about 5, 6 months about 10, 9 months about 13, and 12 months about 15 human years.
What is the average lifespan of a dog by size?
Small breeds average 12-16 years, medium breeds 11-14, large breeds 10-13, and giant breeds 8-11 years. Individual dogs vary with genetics, diet, exercise and healthcare.
Is this dog age calculator really free and private?
Yes. No signup, no account, no watermark, no data collection. All calculations run entirely in your browser with deterministic veterinary formulas - your dog's information never leaves your device.
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