DogTally

Methodology and Sources

Every number our calculators use traces to a published source listed below. When we could not verify a figure against a primary veterinary or breed-registry source, we left it out rather than guess.

Puppy weight predictor

The predictor combines official breed adult-weight ranges, a size classification from the largest published puppy-growth study, and two published estimation formulas. It skips a week-by-week growth curve, because no fetchable source publishes one.

Adult weight ranges cover 38 of the AKC's top 40 most popular breeds (2025 list), from each breed's official standard where it states a weight, or the AKC profile's quick-facts box otherwise. The Cane Corso standard says only "weight - proportionate to height," and the Vizsla gives height with no weight figure. Both are excluded rather than guessed.

Size classes, toy through giant, sort breeds using weight bands from Omni Calculator's dog-size categories: toy under 12 lb, small 12 to 22 lb, medium 22 to 57 lb, large 57 to 99 lb, giant over 99 lb. That's an organizing convention we chose, not a veterinary classification.

The growth-curve research behind the predictor uses a different five-category split, grouped by kilograms rather than these pound bands: Salt et al., PLOS ONE, 2017, built on records from more than 6 million dogs, corroborated by WALTHAM's puppy growth charts (6 million measurements, 50,000 puppies), from under 6.5 kg up to 30 to 40 kg.

Two published formulas fill the growth-curve gap: weight-at-four-months doubling, from Wisdom Panel: "Multiply your pup's weight at four months by two to get an estimate of their adult weight," flagged by Wisdom Panel itself as its least accurate method since it ignores breed size; and linear extrapolation, from Omni Calculator: "Adult weight = (Puppy weight / Puppy age in weeks) x 52," which assumes growth finishes around 12 months and understates it for large and giant breeds.

No fetchable source publishes a week-by-week percent-of-adult-weight table. Salt et al. 2017 publishes its curves only as chart images, and a 2024 correction notice points to a data repository we had no way to query. WALTHAM's charts are the same dataset, graphic-only. And Hawthorne et al., 2004, often cited for this figure, wasn't accessible in full text anywhere we tried. So the predictor blends breed ranges with the two formulas above instead of projecting a curve we cannot verify.

Food calculator

The calculator starts from resting energy requirement (RER): 70 x (body weight in kg)^0.75, per the Merck Veterinary Manual: "The exponential formula (RER = 70 [body weight in kg 0.75]) can be used for animals of any body weight." We use this form, not the linear approximation (30 x kg + 70), which Merck restricts to dogs between 2 and 45 kg.

RER is multiplied by a factor for life stage and activity, from Merck's maintenance energy table and the Pet Nutrition Alliance calorie handout, which agree:

No WSAVA, AAHA, Merck, or peer-reviewed source publishes a distinct weight-gain multiplier for underweight dogs. Blog aggregators citing 1.2 to 1.8x don't trace to a primary source, so we left it out. If your dog needs to gain weight, use the neutered or intact adult factor as a floor and work with your vet.

Calorie density is not standardized across dog food brands; the WSAVA guidelines direct owners to check the specific product. As a default, we use 330 to 420 kcal per cup for dry food, from real product figures reported by PetMD, and 300 to 450 kcal per 13-ounce can for wet food, from a benchmark set by Tufts Petfoodology. These are starting points, not averages. Check your bag's calorie content statement.

Age calculator

The core age-conversion table comes from the American Animal Hospital Association's Canine and Feline Age Chart poster, part of the 2019 AAHA Canine Life Stage Guidelines, citing the Dog Owner's Home Veterinary Handbook (Eldredge et al., 2007). It runs year 1 through year 16 across four size classes: small or toy (20 lb and under), medium (21 to 50 lb), large (51 to 90 lb), and giant (over 90 lb), with full year-by-year values instead of one flat multiplier.

We also offer human_age = 16 x ln(dog_age) + 31, from Wang, Tan, Tian et al., Cell Systems, 202030203-9), a UC San Diego study comparing DNA methylation in 104 dogs and 320 humans. The NHGRI press release covering it states the caveat directly: "the dog-to-human years formula is largely based on data from Labrador retrievers alone," and future studies "will be required to test the formula's generalizability." We present it as Labrador-anchored, not breed-general.

The "1 dog year = 7 human years" rule does not hold up. The AVMA states it plainly: "Contrary to popular belief, dogs do not age at a rate of 7 human years per dog year." Real aging is front-loaded, roughly 15 human years in year one and 9 more in year two, then slower and size-dependent. DogTime quotes Purdue researcher David J. Waters: "eight years in one breed is not equivalent to eight years in another." The 7:1 ratio traces to a 1950s coincidence of average lifespans, per the AKC's account, not a biological finding.

Corrections

If you spot a source we got wrong, a formula we misquoted, or a number that needs updating, email us at contact@dogtally.com. When we can't verify a number against a real source, we leave it out. That's the whole method.

DogTally guides and tools are for information only and are not veterinary advice. Talk to your vet about your dog's health.