PetMath
🥣 Interactive Pet Calculator

Pet Food Portion Calculator

Enter your pet's species, weight, and life stage to get a daily calorie target in kcal — the same resting-energy method veterinary nutritionists start from.

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How the food portion calculator works

Resting energy, then a life-stage multiplier

Veterinary nutrition starts from the Resting Energy Requirement (RER) — the calories a pet burns at complete rest:

RER = 70 × (body weight in kg)0.75

RER is then multiplied by a factor reflecting life stage and activity — 1.6 for a typical neutered adult dog, 1.2 for an adult cat, 3.0 for a young puppy, and so on. The result is the Maintenance Energy Requirement (MER): a starting estimate of calories per day.

From calories to cups

Your pet food's label states its energy density — e.g. "3,800 kcal/kg" or "350 kcal/cup". Divide your daily target by that number to get a daily portion, then split it across meals. Treats should stay under 10% of daily calories; count them in.

It's a starting point, not a prescription

Individual metabolism varies by ±20%. Weigh your pet every 2–3 weeks: gaining unintentionally? Cut back 10%. Losing weight unintentionally? Increase 10%. Puppies, seniors, and pets with medical conditions need professional guidance — this calculator is the floor of that conversation, not the ceiling.

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Frequently Asked Questions

Why does the calculator give calories, not cups?
Cup measures differ between foods; calories don't. "1 cup" of two kibbles can differ by 100+ kcal. Converting to cups yourself using your food's label is the accurate way.
How many meals a day should I split this into?
Adult dogs: two meals. Adult cats: two to four small meals (or puzzle feeders). Puppies under 6 months: three to four. Consistency matters more than the exact split.
My pet needs to lose weight. Which setting?
Use "Weight loss" — it targets RER × 1.0 for dogs (× 0.8 for cats). Do it under vet supervision, weigh every 2 weeks, and never crash-diet a cat: rapid feline weight loss can trigger hepatic lipidosis.
Does this work for raw feeding or homemade diets?
The calorie math is identical — energy is energy. But homemade and raw diets need a nutritionist to balance vitamins and minerals, not just calories. Use the target, then get the recipe professionally balanced.

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⚠️ Veterinary Medical Notice

Our calculators use accepted scientific benchmarks from the AKC, AVMA, and veterinary publications. They are educational screening estimates and never substitute for diagnostic exams by a licensed veterinarian. Read the full disclaimer

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