Methodology & sources
Every formula used on Calc.pet comes from public, peer-reviewed veterinary sources, listed below. No calculator uses private data, AI models, or unsourced estimates — whenever an individual calculator cites a specific source, it also appears on that tool's own page.
| Calculator | Formula | Source |
|---|---|---|
| Human-equivalent age (dog) | 16·ln(age)+31, size adjustment from 6 years | UCSD epigenetic study, Cell Systems (2020) |
| Human-equivalent age (cat) | Scale: 1 year=15, 2 years=24, +4/year after | Widely adopted veterinary consensus |
| Daily calories (RER/MER) | RER = 70×weight(kg)^0.75; MER = RER×factor | AAHA Nutrition Guidelines / WSAVA Global Nutrition Guidelines |
| Food portion | grams = (MER ÷ kcal/kg)×1000 | Direct calculation from MER and manufacturer label |
| Chocolate toxicity | mg of theobromine/kg of body weight | Merck Veterinary Manual / ASPCA Animal Poison Control Center |
| Puppy adult weight | (current weight÷weeks)×52, adjusted by size | Growth proportion rule, common veterinary practice |
| Pregnancy | Dog 58–68 days (avg. 63) · Cat 63–67 days (avg. 65) | Merck Veterinary Manual — Canine/Feline Reproduction |
| Daily water intake | 50–60 ml/kg/day (dog), 40–50 ml/kg/day (cat), wet food adjustment | Merck Veterinary Manual — Nutritional Requirements |
| Body Condition Score (BCS) | 5-question quiz mapped to a 1–9 scale | WSAVA Global Nutrition Committee |
| Vaccine and deworming schedule | Age-based schedule from birth | WSAVA Vaccination Guidelines |
| Food transition | 75/25 → 50/50 → 25/75 → 100% over 7 days | Standard veterinary food-transition practice |
| Annual cost of a pet | Sum of monthly costs × 12 + annual vet cost | Market estimate (industry pricing surveys) |
| Clothing and collar size | Measurement ranges (neck/chest/length) by size | Pet market size charts, approximate reference |
| Daily exercise by breed | Energy group + puppy rule (5 min/month of age) | Common veterinary practice, growth-plate caution |
| Airline travel crate size | Official minimum dimension formula | IATA Live Animals Regulations (LAR) |
| Hot pavement safety | Air/pavement temperature correlation + 7-second rule | FOUR PAWS USA / animal welfare references |
| Heat cycle calculator | 180-day interval (dog) / 14–21 days (cat) | Merck Veterinary Manual — Reproduction |
| Coat color genetics | B/E loci, dihybrid Punnett square | Classic Labrador coat color genetics model |
| Aquarium calculator | Volume, fish per liter, heater wattage, salt dose | General aquarium-keeping rules (approximate) |
| Bird cage size | Minimum dimensions by species | Avian rescue and care references |
| Reptile terrarium | Temperature and UVB by species | Pet reptile care references |
Found an outdated formula or a better source? Every suggestion is welcome — Calc.pet's goal is to keep accuracy above everything else.