About us

We are a small, independent site with free tools for dog owners. We build simple calculators that load fast, work on phones and show their math. We are not vets, and nothing here is veterinary advice.

How we build the tools

• Dog age in human years: the size chart follows the AVMA guide as reported by the AKC (15 years for year one, about 9 for year two, then about 4 to 6 per year by size). Between whole years we draw a straight line. The DNA clock uses 16 × ln(age) + 31 from Wang et al. 2020 in Cell Systems.
• Senior age: from the AVMA rule of the last 25 percent of expected life, using AKC breed life spans.
• Puppy weight: S shaped growth curves fit to weekly weights of 173 puppies in Hawthorne et al. 2004, Journal of Nutrition. We average the breeds in each size class.

Every formula has unit tests. We check each source link before we publish and when we update a page. Last full review: October 22, 2026.

Corrections

If you spot an error, please contact us. We fix confirmed errors fast and note the date.

References

1. Caring for senior cats and dogs, American Veterinary Medical Association
2. How to Calculate Dog Years to Human Years, American Kennel Club
3. Wang T. et al. (2020). Quantitative Translation of Dog to Human Aging by Conserved Remodeling of the DNA Methylome. Cell Systems 11(2)
4. Hawthorne A.J. et al. (2004). Body weight changes during growth in puppies of different breeds. Journal of Nutrition 134(8)
5. Salt C. et al. (2017). Growth standard charts for monitoring bodyweight in dogs of different sizes. PLOS ONE
6. McMillan K.M. et al. (2024). Longevity of companion dog breeds: those at risk from early death. Scientific Reports