How PatiTools calculates things

Every number on PatiTools comes from a published formula or is clearly labelled as our own estimate. This page lists which is which, so you can check our work.

Last updated: October 2026

Food portions

Daily energy need = resting energy requirement (70 × body weight in kg to the power 0.75) × a life-stage factor (for example 1.6 for a neutered adult dog, 1.2 for a neutered adult cat, 2–3 for growth). For overweight and obese adults we follow the AAHA weight-loss approach: calories are based on the estimated ideal weight, 1.0 × RER for dogs and 0.8 × RER for cats. Grams assume 3.6 kcal per gram of dry food, so always check your food's label.

Water

For pets between 2 and 70 kg we use the maintenance formula in the MSD Veterinary Manual: 30 × body weight in kg + 70 mL per day. Outside that range the manual's allometric formulas are used. Our adjustments for activity level (×1.25 high, ×0.9 low) are PatiTools estimates.

Age in human years

The main figure uses a classic size-based table. Its size factors have no primary source, which is why we label it an approximation. For dogs we also show a second estimate from the epigenetic clock study of Wang et al. 2020 (16 × ln(dog age) + 31), which was built from Labrador retrievers only. Life stages (puppy, young adult, mature adult, senior) follow AAHA and AAFP guidance.

Health calendar

Deworming reminders for puppies and kittens follow ESCCAP guidance. Vaccination schedules depend on your country, your area and your vet, so PatiTools only gives generic reminders and never sets your schedule.

Toxic and safe foods

The list is compiled from general veterinary toxicology references such as the ASPCA Animal Poison Control Center, Pet Poison Helpline and the MSD Veterinary Manual. We simplify each entry into four levels: usually safe, caution, toxic and emergency. Real risk depends on the amount, the animal's size and its health, and a food missing from the list is not a food that is safe.

Breeds

Breed pages show typical weight ranges and lifespans for a healthy adult. Individual animals vary a lot, mixed breeds even more. Food, water and exercise figures on those pages are produced by the same tools described above.

What we could not back with a primary source

We looked for primary sources for these and did not find a usable one, so they are PatiTools estimates and are labelled that way on the site:

Daily exercise minutes by species, size and age. We found no veterinary guideline that sets exact minutes.
Ideal weight ranges by dog size. Veterinary guidelines use body condition score rather than size.
Yearly cost estimates. They are indicative and depend heavily on country and clinic.
The size factors of the classic dog-age table.
Our own multipliers for activity, senior dogs and underweight pets.