Sources and method

PuppySizer only states facts that trace to a source on this page. Each source was read on the date shown, and the site was checked against all of them on November 8, 2026. If a source changes, the page that uses it should change too; if you spot a mismatch, write to [email protected].

Puppy weight and breed growth

The growth curves are from Salt et al. (2017), who modelled the weights of dogs in the records of Banfield Pet Hospitals. The paper publishes the curves as charts for five size classes, one chart each, with a female and a male panel and nine centile lines (0.4th, 2nd, 9th, 25th, 50th, 75th, 91st, 98th, 99.6th) from 12 weeks to 2 years. There is no table of values, so we read the lines off the published figures with a script (in the repository under sites/puppysizer.com/data-sources), at 27 ages. The reading is accurate to about half a percent of the axis range and the output is checked in the tests against values read by eye from the charts.

To predict an adult weight we find where the puppy sits between the centile lines at its age (interpolating in log-weight between neighbouring lines), keep that position, and read the weight at 104 weeks. The range is half the distance between neighbouring lines either side of that position, the tolerance the authors used to call a breed-specific curve consistent with a size-class curve. This is our reading of how to express uncertainty, not a figure from the paper.

For a puppy of unknown size we try each of the five classes and keep those whose projected adult weight lies inside that class's own adult-weight bounds (class I under 6.5 kg, II 6.5 to 9 kg, III 9 to 15 kg, IV 15 to 30 kg, V 30 to 40 kg). The range spans them.

Breed pages: the weight range is the American Kennel Club figure for the breed, numbers only, read on November 8, 2026. The growth curve is the size-class curve through the middle of that range (or through the single weight or limit AKC gives, and the page says which). 60 breeds are covered, each once, with the poodle sizes as separate breeds. Breeds whose adult weight is above 40 kg get the AKC weight and no curve, because the paper could not model giant breeds.

Calories

RER = 70 × weight in kg raised to the power 0.75, times a life-stage factor from the table in the Merck Veterinary Manual article on nutritional requirements of small animals. The 30 % range and the 10 % treat limit come from the Merck Manual and the 2021 AAHA nutrition guidelines.

Pregnancy

Due-date windows are the days given in the Merck Veterinary Manual article on whelping and queening. The milestone dates (implantation, blood test, ultrasound, X-ray) are from its article on pregnancy determination, and are shown only when you start from an LH surge date, since that is the reference point they are measured from.

Poison calculators

Chocolate, grape and raisin, and xylitol thresholds are quoted from the Merck Veterinary Manual toxicology articles. The calculators do the arithmetic (amount × concentration ÷ body weight) and show the reference level. They never say “safe”, and every result tells you to contact a vet or poison hotline. See the medical disclaimer.

Age

The AVMA “PETS age faster than PEOPLE” chart gives the human-year figures, for cats and for a medium-sized dog, ages 1 to 16; we interpolate linearly between whole years. The DNA-based formula (Wang et al. 2020) is shown for comparison.

What PuppySizer cannot do

• It cannot examine your pet, tell you a dog is healthy, or replace a vet.
• Growth estimates do not cover puppies under 12 weeks, dogs over two, or giant breeds.
• Individual dogs and cats vary. Ranges are guides, not guarantees.