Dog Age Calculator
Convert your dog age to human years. Pick the size of your dog and compare three methods: a size-based chart, the 2019 epigenetic formula and the old 7x rule.
How the dog age calculator works
The old rule that one dog year equals seven human years is too simple. Dogs mature fast in the first two years, then age at a rate that depends on their size. Larger dogs age faster after year two than small dogs.
This calculator gives you the size-based chart used by many vets (15 human years for year one, 9 more for year two, then 4, 5 or 6 human years for each dog year depending on size). It also shows the 2019 formula from researchers at UC San Diego, which compares DNA changes in dogs and humans.
The formulas
Example: A 5 year old medium dog is about 39 years in human years by the size-based chart and about 57 years by the epigenetic formula. The 7x rule would give 35 years.
These are estimates. Breed, health and genetics change how a dog ages, so use the result as a guide and ask your vet about senior care.
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Frequently asked questions
How old is a 5 year old dog in human years?
About 35 to 57 human years depending on the method. A medium dog is about 39 by the size-based chart.
Is one dog year really seven human years?
No. Dogs age quickly in the first two years and then more slowly, so the 7x rule is only a rough guide.
Do large dogs age faster than small dogs?
Yes. After the second year, large breeds add more human years per dog year than small breeds, and they usually have shorter lives.
When is a dog considered a senior?
Often around 7 years for large dogs and 10 years for small dogs, but your vet can advise based on health.
How accurate is the dog age calculator?
It is an estimate. Genetics, diet, exercise and health all change how fast an individual dog ages.
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