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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.

Pregnancy calculator

The pregnancy calculator starts from the "about 63 days" figure most owners have heard, then narrows or widens the estimate based on which date type you enter. Sources agree on the biology and differ only on which day they call day zero. From ovulation, gestation runs approximately 63 days, per Cornell and the AKC. From the LH (luteinizing hormone) surge, the Merck/MSD Veterinary Manual puts term at 64 to 66 days, since ovulation happens about two days after the LH surge. From a vaginal-cytology diestrus shift, a clinical staging method, Merck gives 56 to 58 days later. From breeding date, the least reliable anchor, the AKC's range widens to 58 to 72 days, because fresh semen can stay viable for over nine days, per Merck, and mating doesn't line up closely with actual ovulation. The calculator narrows the window for ovulation or LH-surge dates, and widens it for breeding date alone.

Week-by-week milestones, implantation around day 15 to 23, palpable uterine swellings near day 21, detectable heartbeats by ultrasound day 25 to 35 or by day 28 to 30 per the AKC, visible toes at day 35, radiograph-detectable skeleton at day 42 to 45, nesting behavior at day 58 to 62, are sourced to Cornell, the AKC, and Merck's "Pregnancy Determination in Bitches and Queens" page. Merck notes abdominal palpation "is not as reliable as other methods" for counting puppies or confirming viability, so the calculator treats palpation as a rough early signal only.

Litter-size figures come from two sources that disagree and are shown separately rather than merged. The AKC publishes breed averages from registration data (French Bulldog 3, Labrador Retriever 7, German Shorthaired Pointer 9) and an overall range of 1 to 12 puppies, average 5 to 6. A peer-reviewed study, Borge et al., Theriogenology, 2011 (10,810 litters, 224 breeds, Norwegian Kennel Club records), breaks litter size down by body weight instead: miniature (under 5 kg) 3.5 average, small 4.2, medium 5.7, large 6.9, giant (over 45 kg) 7.1. The journal's abstract page returned an HTTP 403, so this table traces to a secondary page that reproduces and cites the study; the study's existence and headline numbers are corroborated elsewhere.

Whelping-time guidance, temperature drop to roughly 99°F 8 to 24 hours before labor, up to two hours as a normal gap between puppies, is corroborated across Cornell, the AKC, Merck, and VCA Animal Hospitals. Birth complications are a veterinary emergency, not a calculator question: if your dog strains more than 30 minutes without a puppy, or it's been over two hours between puppies, call your vet.

Vaccine schedule

The vaccine schedule generator is built on the 2022 AAHA Canine Vaccination Guidelines, peer-reviewed and published in the Journal of the American Animal Hospital Association. AAHA's own site blocked our direct fetch requests, so we used two AAHA-authorized mirrors instead: the full guideline PDF hosted by Merck Animal Health, an AAHA sponsor, and the 2024-updated Table 2, hosted on AAHA's own HubSpot content account. Both carry the AAHA copyright line and match the published guideline.

Core vaccines (distemper, adenovirus, parvovirus, with or without parainfluenza) start at 6 to 8 weeks, doses every 2 to 4 weeks until at least 16 weeks old, 18 to 20 weeks preferred in high-risk areas. A booster follows within a year, then boosters every three years; AAHA states directly that "annual boosters are not necessary." Rabies has no AAHA-stated minimum age since it defers entirely to law, though the vaccine is labeled from 3 months old: "Age at initial vaccination, timing of booster doses, vaccine formulation... may all be stipulated in laws or regulations." A first booster is recommended one year after the initial dose regardless of product; after that, the interval depends on the product's 1-year or 3-year duration-of-immunity label and local law.

One classification changed between guideline versions: the 2022 text lists leptospirosis as noncore; the 2024-updated Table 2 moved it into the core block. The dosing schedule (two doses starting at 12 weeks, 2 to 4 weeks apart, annual boosters) didn't change, only the tier, and our generator follows the 2024 table. Lifestyle (noncore) vaccines, Lyme disease, Bordetella and parainfluenza, and canine influenza, are dosed per Table 2 and surfaced only with AAHA's risk context: Lyme for tick-endemic regions, Bordetella and parainfluenza for boarding or daycare, influenza where local circulation warrants it. AAHA states directly: "the routine use of CIV vaccines in all dogs is currently not recommended."

State rabies-law variation is marked lower confidence on purpose. Our figure that 39 states mandate rabies vaccination, with 11 having no statewide requirement, and the claim that local jurisdictions can impose stricter, but not more lenient, requirements than the state, came from a WebSearch summary, not a direct fetch of avma.org, which returned 404s. Treat those specifics as unverified. AAHA does directly confirm that mandates "can exist at the local, state, and provincial levels." Check your local law and your vet for the rabies schedule, not this tool.

Crate size chart

The crate size chart publishes manufacturer size-to-weight tables separately rather than averaging them, because they don't agree closely enough to merge. MidWest Homes for Pets' iCrate line runs seven sizes from 18 inches (up to 10 lbs) to 48 inches (90 to 110 lbs), published in MidWest's own product copy and cross-checked against MidWest's site. Petmate publishes two lines that disagree at both ends: the Vari Kennel tops out at 40 inches (70 to 90 lbs), while the Sky Kennel goes to 48 inches (90 to 125 lbs), and the lines' smallest sizes differ too (19 inches at up to 10 lbs versus 21 inches at up to 15 lbs). Both Petmate tables, from petmate.com, are published as-is, with no reconciliation applied.

For the "measure your dog" sizing rule, sources vary on how many inches to add for clearance. MidWest says "a few inches" without a number. Petmate gives 3 to 4 inches added to both height and length; Chewy gives 4 inches. The chart uses the Petmate and Chewy figures, since both are exact and close together, and flags MidWest's looser wording rather than inventing a number.

Petco and PetSmart's sizing pages both returned an HTTP 403 to our fetch tool and could not be verified. We excluded them rather than guess. Check those retailers' pages directly if you shop there.

Water intake calculator

The water intake calculator is the one page on this site where sources genuinely disagree, so we show every published figure with attribution instead of averaging them. Converted to mL per kg body weight per day, published figures run from 20 mL/kg (low end, Vet Specialists Ltd, a UK referral practice) to 80 mL/kg (high end, Whole Dog Journal, attributed to "internal medicine specialists"), roughly a 4x spread. In between: PetMD and Hill's Pet Nutrition both give the commonly cited figure of about 1 oz per lb per day (roughly 62.5 mL/kg/day), the AKC gives 40 to 60 mL/kg/day, and the Merck/MSD Veterinary Manual gives 44 to 66 mL/kg/day, a general mammalian figure, not dog-specific, from a clinical maintenance-fluid page rather than a healthy-drinking source. None of these figures traces to a primary peer-reviewed study. We show ~1 oz/lb/day as the commonly cited planning figure alongside the mL/kg range, rather than picking a winner.

The overdrinking (polydipsia) threshold has strong agreement: both the AKC and Vet Specialists Ltd independently give 100 mL/kg/day as definitively increased intake, with Vet Specialists naming 60 to 100 mL/kg/day as a "grey zone" needing a baseline comparison. The calculator uses 100 mL/kg/day as its call-your-vet flag. Polydipsia can signal diabetes, kidney or liver disease, Cushing's syndrome, or infection, per the AKC and Whole Dog Journal, and it's a veterinary question, not a hydration one, once your dog crosses that line.

One source we tried and couldn't use: the 2024 AAHA Fluid Therapy Guidelines PDF fetched as unparseable binary content, so we couldn't pull a figure from it. A stronger AAHA-sourced water number should replace the range above if one becomes available.

Toy durability pages

DogTally's toy durability pages compare manufacturer size tables and durability claims across six brands: Kong, West Paw, Goughnuts, Benebone, Nylabone, and Tuffy. Three brands, Kong, Goughnuts, and Nylabone, publish exact per-size dog-weight-in-pounds tables directly on their own product or sizing-guide pages, fetched directly and confirmed. West Paw publishes no weight table at all for its Toppl or Tux lines; it markets by chewer intensity, "Built For Moderate Chewers," and by product dimensions or treat capacity instead, so no weight range appears for those products rather than one estimated from third-party review sites. Benebone's Wishbone weight table is corroborated across two independent WebSearch passes that both cite benebone.com, but a direct fetch of the page didn't render the size-guide text, likely client-side rendering, so that table is flagged lower confidence rather than presented as directly verified. Tuffy has no manufacturer weight table of any kind; its products are sized by dimension only.

Every "toughest," "most durable," or "power chewer" line on these pages is a brand's own marketing claim about its own product, captured as an attributed quote, never restated as a DogTally assertion. Kong's "Its unique, natural rubber formula offers ultra-durability" and "For the most powerful chewers, the black KONG Extreme is the ultimate challenge" both come directly from kongcompany.com. West Paw's "We're 100% confident in the durability and safety of everything we make" is attributed to CEO Spencer Williams on the company's own Love It Guarantee page. None of these lines is a third-party lab test or a veterinary durability study, and the pages say so: chewer-style categorization reflects each brand's own claim about its own product, not independent verification by DogTally or anyone else.

Guarantee terms are recorded the same way, quoted and attributed rather than restated as fact. Goughnuts publishes the most direct promise found in this pack, "If your dog chews through or damages any toy in any way, Goughnuts will replace your toy," with two concrete replacement paths: a $9.65 return-shipping check, or $20 paid up front for a ship-first replacement. West Paw's Love It Guarantee covers toys and treats for 6 months from purchase, one replacement per design per household, and excludes normal wear and tear. Kong's guarantee is a 60-day satisfaction guarantee against defects, not a chewing-damage guarantee, and that distinction matters: a dog destroying a toy through normal chewing isn't the same thing as a manufacturing defect. Benebone offers only informal language, "we'll make it right," with no dollar amount or time window attached. Nylabone and Tuffy: no guarantee terms turned up in this research pass, and the pages say so rather than guessing at one.

A handful of figures on these pages carry a lower-confidence label because they came from a WebSearch result snippet instead of a direct page fetch that returned usable content. Kong's 60-day guarantee terms are sourced from a Zendesk help-center article that returned an HTTP 403 error on direct fetch. Benebone's full Wishbone size table and its two FAQ durability quotes are sourced the same way, after Benebone's FAQ page loaded only header and contact-link chrome with no answer text present in the fetched page. Tuffy's Tuff Scale ratings and its layered-construction claims come from WebSearch aggregation of retailer product pages that cite Tuffy's own rating system, since thetuffys.com's own homepage publishes no numeric scale legend. Prices for Benebone, at every size, and for Nylabone's Power Chew line could not be confirmed in this pass: Chewy returned an HTTP 429 rate-limit error on repeated attempts, and neither manufacturer's own product page rendered a price field to a direct fetch. Those price cells are left blank rather than filled from a third-party retailer that might not reflect the brand's current price.

Safety framing on these pages, supervise your dog, inspect toys regularly, replace anything cracked or missing pieces, comes from three independent animal-welfare organizations rather than from any toy manufacturer: the ASPCA's position statement on dog chews and treats, the American Humane Society's toy-safety guidance, and Humane World for Animals' toy-picking guidance. That split is deliberate. Durability and "how tough is this toy" claims come from the brands selling the toys; supervision and safety guidance comes from organizations with no product to sell.

Corrections

If you spot a source we got wrong, a formula we misquoted, or a number that needs updating, email us at [email protected]. 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.