Pet Calculators for Dogs and Cats

How TailCalc works

Each calculator runs in your browser. The page opens with a result already filled in, from a stated set of defaults, so you can see the shape of the answer before you type. Changing a weight, a birth date or an age updates that result on the page. Nothing you type is sent to a server.

Feeding pages turn body weight into resting energy with the exponential formula in the Merck Veterinary Manual, then multiply by the factor for the life stage. Adult dogs use neuter status and body shape. Adult cats use neuter status, and a separate control for the obesity-prone row. Puppies switch from 3 times resting energy to 2 times at 4 months. Kittens stay on 2.5, and the page says they may be fed free choice. Cups and cans use the kcal you type from the label. The numbers that load with the page are examples.

The raw dog food page is the exception. It converts a percent of body weight into grams, with an optional example split of muscle meat, bone and organ. Above that explanation is the AVMA's position: raw or undercooked animal-source protein is discouraged because of pathogen risk. The percent opens as an example you replace. It is not a claim that raw feeding is better.

Weight pages do not pretend to be a diagnosis. Puppy adult size opens with a labelled example and a wide band, not a month-by-month curve. Kitten weight is a wide band built from Merck's birth weight and weekly gain. Dog and cat ideal weight comes from a 9-point body condition score, using AAHA's figure of about 10% overweight for each point above 5. Scores under 4 do not get an invented target.

Vaccination pages list typical timing. The puppy page uses the 2022 AAHA canine guidelines and shows weeks until you enter a birth date. The adult dog page counts 3 years forward from the last core dose and does not date rabies. The kitten and cat page follows the 2020 AAHA/AAFP guidelines, including a booster at 6 months rather than at 1 year. Your vet's plan, and local rabies law, decide the real schedule.

Age pages compare a published formula with a popular shortcut, or mark a life stage. The dog calculator and the dog chart use a DNA formula from a 2020 study of 104 dogs, mostly Labrador retrievers, printed beside the old multiply-by-seven rule. There is no size column. The cat calculator and the cat chart use the American Association of Feline Practitioners life stages chart for both the human-year line (15, then 24, then 4 per year) and the stage names.

Why the numbers are estimates

Merck says an individual dog or cat may need as much as 30% more or less food energy than the formula. Vaccine guidelines describe a series, then tell the clinician to follow the product and the law. Age formulas compress a life into one equation that was fit on one kind of dog. TailCalc prints the source, the year and the limit under the result. It does not print a dose, a toxin threshold, a diagnosis or a "safe to eat" answer.

Health information

These pages are general information for dog and cat owners. They are not veterinary advice, a prescription or a diagnosis, and they do not create a vet-client relationship. Ask your vet. In an emergency, contact a vet. Do not change a diet or skip a vaccine because a calculator produced a number.

Sources behind the tools that are live

• Merck Veterinary Manual, nutritional requirements of small animals(resting energy and maintenance factors).
• Merck Veterinary Manual, feeding practices in small animals(treats under 10% of calories, puppy meals, kitten birth weight and weekly gain, adult cat averages).
• 2021 AAHA nutrition guidelines, screening evaluation(about 10% overweight for each body-condition point above 5).
• 2021 AAHA weight reduction in the obese pet(weight-loss starting intakes for dogs and cats, on ideal weight).
• NHGRI news release on the 2020 dog-aging study(human age = 16 ln(dog age) + 31; 104 dogs, mostly Labrador retrievers).
• 2020 AAHA/AAFP core vaccines for pet cats(FeLV: two doses, 3–4 weeks apart, from as early as 8 weeks).
• AVMA policy on raw or undercooked animal-source protein(raw diets are discouraged because of pathogen risk).
• 2022 AAHA Canine Vaccination Guidelinesand thecurrent core-vaccine table(core combination every 3 years after the first booster; rabies as required by law).
• 2020 AAHA/AAFP Feline Vaccination Guidelinesand theguideline FAQs(kitten series, 6-month booster, FeLV for adults).
• 2021 AAHA/AAFP feline life stage definitions(kitten, young adult, mature adult, senior).
• AAFP feline life stages chart(cat years to human years: 15, then 24, then 4 per year).
• Cornell, the normal whelping process(about 63 days; wider from a breeding date, tighter from ovulation).
• Merck Veterinary Manual, management of reproduction of cats(60 to 65 days, and typical delivery 64 to 66 days after breeding).

Pregnancy pages give a window, not one morning. For dogs, Cornell's whelping page is the headline: about 63 days, tighter when ovulation is known and wider from a breeding date. A Merck chapter states a different breeding span, and the page shows it rather than averaging the two. For cats, the Merck owner chapter states both "60 to 65 days" and "typically 64 to 66 days after breeding." Weight-loss calorie figures stay AAHA's published range. The vet still sets the plan.