Dog age calculator
Convert your dog’s age with the modern logarithmic formula and by size.
- Instant
- Free
- Private (processed locally)
- No sign-up
Forget “× 7”, here comes the science
Dogs do not age at a constant rate. This tool offers two reliable approaches: the logarithmic formula from a DNA study and the veterinary chart by size, more accurate based on weight.
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Enter the dog’s age
In years (half-years accepted).
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Choose the size
Small, medium or large — it changes the estimate.
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Compare
Human age by size and by the logarithmic formula.
Human age by size (excerpt)
| Dog age | Small | Medium | Large |
|---|---|---|---|
| 2 yr | 24 | 24 | 24 |
| 5 yr | 36 | 36 | 36 |
| 8 yr | 48 | 51 | 55 |
| 10 yr | 56 | 60 | 66 |
Logarithmic formula: human age = 16 × ln(age) + 31. E.g. 5 yr ≈ 57 human years. These values are estimates.
Frequently asked questions
Is the “1 year = 7 years” rule accurate?
No, it is a myth. Dogs age very fast in the first two years then more slowly, and the rate depends on size. Multiplying by 7 overestimates young dogs and often underestimates large senior dogs.
What is the logarithmic formula?
A 2019 DNA (methylation) study proposes: human age = 16 × ln(dog age) + 31. At 1 year, a dog already equals ~31 human years; at 5 years, about 57. It reflects the fast aging of youth.
Why does size change the result?
Small dogs live longer and age more slowly after maturity; large dogs age faster. From age 6, the by-size chart diverges: at 10 years, a small dog equals ~56, a large dog ~66.
Which method should I choose?
For a quick, uniform estimate, the logarithmic formula works. For a dog whose weight you know, the by-size chart is more representative. Both remain approximations: your vet is the reference.