How this calculator works
The medium-dog option interpolates the AVMA age guide. The Labrador option applies a natural-logarithm relationship fitted to DNA methylation. We limit that option to adult ages to avoid misleading extrapolation in very young puppies. Neither model predicts remaining lifespan or replaces a veterinary examination.
Formula
Medium dog: 15 human years for year one, 9 more for year two, then 4 per dog year. Labrador: human comparison = 16 ln(dog years) + 31.
Worked example
A five-year-old medium dog compares with 24 + 4 × 3 = 36 human years. A one-year-old Labrador gives 16 ln(1) + 31 = 31 in the methylation model. Different methods describe different aspects of ageing.
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Frequently asked questions
Why not multiply by seven?
Dogs mature rapidly at first, so a single multiplier does not describe all life stages.
Can I use the Labrador model for any breed?
The original sample was Labradors. Applying its result to other breeds has unmeasured uncertainty.
Where are small and giant breed comparisons?
This tool does not invent breed-size corrections. Ask your veterinarian about life stage for your dog's size and breed.