Every number has a source.
The tools on PawsRuler don’t invent their own formulas. Each one uses a published chart, guideline or veterinary reference, says which, and links to it.
Where the numbers come from
We use veterinary and professional references that publish their figures openly:
- Age in human years: the American Kennel Club’s chart for dogs, by adult size, and the American Veterinary Medical Association’s chart for cats.
- Feeding: the resting-energy formula and life-stage factors in the 2021 AAHA Nutrition and Weight Management Guidelines, and WSAVA’s advice on treats.
- Growth and weight: PetMD’s veterinarian-written milestone rules for puppies, the WALTHAM puppy growth charts, the ASPCA kitten age and weight chart, and PetMD’s adult cat weights by breed.
- Pregnancy: the Merck Veterinary Manual for dogs and VCA Animal Hospitals for cats.
- Gear sizes: the American Kennel Club’s crate, collar and harness guides, and the AAFP feline behavior guidelines and the ASPCA for litter boxes.
Each tool page lists its sources at the bottom, with what we took from each one. The numbers were last checked against those sources on Oct 17, 2026.
How the tools use them
Where a source gives a table, the tool looks the answer up in that table. Where a source gives a formula, the tool runs it and shows the steps. Where a source gives a range, the tool shows the range rather than a single number that looks more precise than it is. When the tool has to fill a gap, such as an age between two birthdays, it says so next to the result.
What the tools won’t do
PawsRuler gives starting points for everyday questions. It doesn’t diagnose, calculate medication doses, judge whether something your pet ate is dangerous, or plan care for a pet who is ill, pregnant, nursing or losing weight. Those questions belong with your veterinarian, and the tools say so where they come close.
Independence
We aren’t affiliated with any of the organizations we cite, and none of them reviews or endorses this site. Naming a source means we used its published figures, nothing more.
Found a mismatch?
If a number doesn’t match the source it cites, tell us. We check it against the source and correct the tool.