petculate

Methodology & Sources

Every calculator on this site implements a published veterinary formula, unmodified, with its source named and its limitations stated. This page is the audit trail. If you find an error, the about page explains how to reach us. Corrections ship fast.

Energy: RER and life-stage factors

The dog calorie, dog food, puppy feeding, and cat calorie tools all start from the Resting Energy Requirement:

RER (kcal/day) = 70 × (body weight in kg)^0.75

This is the exponential form recommended by the WSAVA Global Nutrition Committee, validated for roughly 0.5–120 kg (we reject inputs outside that range rather than extrapolate). Daily targets multiply RER by a life-stage factor: 3.0 for puppies under 4 months, 2.0 for puppies to 12 months, 1.6 for neutered adults, 1.8 for intact adults, 1.4 for seniors, 2.5 for very active dogs (published range 2.0–5.0), 1.0 at ideal weight for weight loss, 1.4 at ideal weight for weight gain (published 1.2–1.8), 3.0 for late pregnancy, and 4.0 for lactation (published 4.0–8.0). Feline factors: 2.5 for kittens (published 2.0–2.5), 1.2 neutered, 1.4 intact, 0.8 for weight loss, 1.1 senior.

Limitation: factors are ranges compressed to a point estimate; individual metabolism varies roughly ±20%. That's why every result panel says to verify against monthly weight and body condition.

Dog age: two methods, both shown

The dog age calculator's primary answer is the size-adjusted chart published by the American Kennel Club and consistent with AAHA life-stage guidance: year one = 15 human years, year two = 24 total, then per-year increments that grow with size class (about +4 small, +5 medium, +6 large, +7 giant). We interpolate linearly for fractional years, map puppies under one year to developmental milestones, and extrapolate past year 16 using each size's final increment.

The secondary answer is the epigenetic clock from Wang et al. (2020, Cell Systems): human age = 16 × ln(dog age in years) + 31, derived from DNA-methylation profiles of 104 Labrador Retrievers.

Limitations we enforce in code: the logarithmic formula goes negative below ~2 months and is not meaningful under one year, so we only show it from age 1; and because the cohort was a single breed, we label it "Labrador-derived" wherever it appears. The two methods answer different questions, and the dog years guide walks through the disagreement.

Cat age

The cat age calculator uses the AAHA/AAFP feline life-stage convention: 15 human years for year one, 24 by year two, +4 per year after, with kitten months interpolated (6 months ≈ 10 human years). Cats' narrow size range makes a single curve appropriate.

Raw feeding percentages

The raw food calculator uses the community-standard 2–3% of adult body weight per day and age-banded puppy percentages (8% under 4 months, 6% to 6 months, 4% to 9 months, 3% to 12 months). Important context: these are portion conventions, not an endorsement. The AVMA discourages raw animal-source protein diets and the FDA has documented pathogen contamination in commercial raw foods. We present the math with the safety evidence beside it.

What we deliberately don't do

Primary sources