Dog age calculator
Enter your dog’s age and size to see their age in human years, their life stage and a full dog-years chart.
In human years, your dog is about
Adult dog (5 years old)
Comparison: about 57 human years by the formula 16 × ln(age) + 31 from a 2020 study of Labrador retrievers. It is a comparison, not a rule for every breed.
Life stages for a medium dog
Dog years to human years: medium dog
| Dog age (years) | Human years |
|---|---|
| 1 | 15 |
| 2 | 24 |
| 3 | 29 |
| 4 | 34 |
| 5 | 39 |
| 6 | 44 |
| 7 | 49 |
| 8 | 54 |
| 9 | 59 |
| 10 | 64 |
| 11 | 69 |
| 12 | 74 |
| 13 | 79 |
| 14 | 84 |
| 15 | 89 |
| 16 | 94 |
How to use the dog age calculator
- Enter your dog’s age in years and months.
- Choose the size group that matches your dog’s adult weight.
- Read the age in human years, the life stage, the timeline and the chart. The results update as you type.
How the calculation works
Dogs age fastest in their first two years. This calculator counts the first year as 15 human years and the second year as 9 more, so a 2-year-old dog is 24 in human years. After that, each dog year adds 4 human years for a small dog, 5 for a medium dog, 6 for a large dog and 7 for a giant dog, because larger dogs age faster on average. The life stage (puppy, adult or senior) also depends on size.
The smaller comparison figure uses the formula 16 × ln(dog age) + 31, taken from a 2020 study of Labrador retrievers that looked at changes in DNA methylation. It is shown only for comparison and is not a rule for every breed.
Frequently asked questions
Is one dog year really seven human years?
No. The “7 years” rule is a rough shortcut. Dogs mature much faster than that in their first two years, and the rate after that depends on size, so this calculator uses a different curve for each size group.
Why does a dog’s size matter?
On average, larger dogs have shorter lifespans and show signs of ageing earlier than small dogs, so each year after the age of 2 counts for more human years in a large or giant dog.
How do I pick the size group?
Use your dog’s adult weight: Small is under 9 kg, Medium is 9 to 23 kg, Large is 23 to 45 kg and Giant is over 45 kg. For a puppy, use the weight you expect it to reach as an adult, and ask your vet if you are not sure.
Why are there two estimates?
The main figure uses the size-based formula. The smaller figure comes from a different method, a study of Labrador retrievers, and often gives a different number. Neither is exact for every dog, because breed, health and genetics all matter.
Does this replace vet advice?
No. It is an estimate for general interest. Ask your vet about your dog’s health, food, vaccinations and care at each life stage.
An estimate for general interest, not veterinary advice.
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