The Veterinary Formula Behind Feeding

Pet nutrition starts from resting energy requirement: RER = 70 × (weight in kg)^0.75. This is the same formula veterinarians use, and it exists because calorie need scales with metabolic mass, not pounds — a 10 lb cat needs proportionally more than a 100 lb dog. Activity (1.4–2.0× for dogs, 1.1–1.4× for cats) and life stage (2× for growing animals, 0.9× for seniors) then adjust the baseline.

Calories, Not Cups

Feeding guides on bags assume a generic pet, but calorie density varies widely: dry dog food runs 350–450 kcal per cup, wet food is far lower per ounce because of water content. The calculator converts your pet's true calorie need into cups or ounces using standard calorie densities — the honest way to compare two different foods is calories, not portion size.

Budget the Bag

Monthly food cost is monthly pounds × price per pound: about 20 lb and $60 for a 40 lb dog on mid-priced food, 6 lb and $18 for a 10 lb cat. Premium foods cost more per pound but are calorie-dense, so the cost per day climbs less than the sticker suggests. The calculator's price field makes any bag comparable on monthly dollars.