Dog Years Calculator
Convert your dog's age to human years using the modern formula.
Small: under 20 lbs · Medium: 20–60 lbs · Large: 60+ lbs
Enter your dog's age to calculate
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Frequently Asked Questions
How are dog years calculated?
The old "1 dog year = 7 human years" rule is an oversimplification. A more accurate formula: the first year equals about 15 human years, the second about 9 more (total ~24), and each year after that roughly 4-5 human years depending on breed size. Large breeds age faster than small breeds.
How old is my dog in human years?
Use the modern formula: first 2 years = 12.5 human years each (25 total), then add 4 years for each subsequent year. Adjust for size: small dogs age about 10% slower, large dogs age about 10% faster. A 5-year-old medium dog is roughly 33 in human years.
Do big dogs age faster than small dogs?
Yes — larger breeds tend to have shorter lifespans and age more quickly. A Great Dane at age 7 is considered a senior, while a Chihuahua at 7 is still middle-aged. The reason is thought to be related to growth hormones and cellular aging rates that scale with body size.