Dog & Cat Food Portion Calculator
Enter your pet's ideal body weight, its activity level, and the calorie density of its food, and this calculator estimates the daily energy it needs and how many cups that works out to. It uses the resting energy requirement (RER) formula that veterinarians use as a starting point — an estimate to sanity-check portions, not a substitute for veterinary advice.
Estimate only — confirm portions with your veterinarian.
Cups per day
1.80
630 kcal/day ÷ 350 kcal/cup
Resting need (RER)
394
Daily energy
630
Daily kcal by activity level
Daily kcal by activity
Compare scenarios
Run the same calculation with two or three input sets side by side. Differences are highlighted; every number comes from the same tested formula as the calculator above.
| Input | Scenario A | Scenario B |
|---|---|---|
| Weight Kg | ||
| Lifestyle Factor | ||
| Food Kcal Per Cup |
How it works
The foundation is the resting energy requirement (RER): the calories an animal burns at rest, which scales with metabolic body size, not linearly with weight. The standard formula is RER = 70 × (body weight in kg)^0.75. The 0.75 exponent matters — a dog twice as heavy needs less than twice the calories, because larger bodies are metabolically more efficient per kilogram.
Daily maintenance energy is RER multiplied by a lifestyle factor that reflects activity and life stage. Common reference values are around 1.6 for a neutered adult at normal activity, 1.8 for an intact adult, 1.0 for a weight-loss target, and 2.0–3.0 for a growing puppy or kitten. So a 10 kg neutered adult dog needs about 70 × 10^0.75 × 1.6 ≈ 630 kcal per day. Portion size then is daily calories divided by the calories per cup printed on your food's label.
Two cautions make this an estimate, not a prescription. First, calorie density varies enormously between foods — from roughly 250 to over 500 kcal per cup — so always use your specific label. Second, individual metabolism, body condition, treats, and health conditions all shift the real requirement. Weigh your pet regularly and adjust: the scale and your vet's body-condition assessment are the true feedback loop, not any formula.
Frequently asked questions
Should I use my pet's current weight or ideal weight?+
Use the ideal (target) weight, especially if your pet is overweight. Feeding to maintain an already-heavy weight just keeps the animal heavy; feeding to the ideal weight, combined with a weight-loss lifestyle factor around 1.0, creates the modest calorie deficit needed to slim down safely. If your pet is at a healthy weight, current and ideal are the same. When in doubt about what the ideal weight is, ask your vet for a body-condition-score target — it's more reliable than a breed-average number.
Why does the calculator use body weight to the 0.75 power?+
Because metabolic rate doesn't scale linearly with body mass — it scales with roughly the 3/4 power, a well-established biological relationship (Kleiber's law). In plain terms, bigger animals burn fewer calories per kilogram than smaller ones. Using a simple 'X calories per kg' rule would badly overfeed large dogs and underfeed small ones. The RER formula's 0.75 exponent captures this, which is why veterinary nutrition guidelines (WSAVA, AAHA) use it as the starting point for feeding calculations.
Is this a replacement for my veterinarian's advice?+
No. This is an estimate to help you sanity-check feeding amounts and understand the math behind them. It can't account for your pet's specific metabolism, health conditions, medications, reproductive status, or the treats and table scraps that add up during the day. Puppies, pregnant or nursing animals, and pets with medical conditions have needs this general formula doesn't address. Always confirm portions with your veterinarian and monitor your pet's body condition and weight over time, adjusting as needed.