How much should my dog eat? The RER/MER formula, explained
PetCost Editorial Team · Figures cross-checked against NAPHIA, AKC and veterinary RER/MER guidance · Updated 2026-06-02
Feeding guidelines on the bag are averages. Here's the actual vet formula for your dog's calories — and how it translates into cups per day and dollars per year.
The formula vets use
RER (Resting Energy Requirement) = 70 × (kg)^0.75. Multiply by a Maintenance Energy Requirement factor — about 1.2–1.4 for inactive/senior dogs, 1.6 for typical neutered adults, up to 2.0+ for very active or working dogs. That gives daily calories. Divide by your food's kcal-per-cup (commonly ~340 for dry food) to get cups per day.
From cups to dollars
Multiply cups per day by 30 to get monthly volume, convert to pounds, and price at your food's cost per pound. This is exactly how we compute every breed's food cost — see the live figure and a cumulative-over-lifetime chart on any breed page, or rank breeds by how much they eat.
Why bag guidelines mislead
Bag charts assume an 'average' dog and often over-portion, contributing to canine obesity (a leading driver of vet costs). The RER/MER calculation is individualized to weight and activity. Always adjust for body condition and confirm with your vet, especially for puppies, seniors or pregnant dogs.
FAQ
How many cups should I feed my dog?
Roughly 0.5–1 cup per 10 lb of body weight per day for a typical adult — calculate precisely with the RER/MER formula above.
How is dog food cost calculated?
From body weight via the RER/MER calorie formula, converted to cups, then pounds, then priced at the food's cost per pound.
Which dogs eat the most?
The largest breeds — intake scales with metabolic body weight. See our 'dogs that eat the most' ranking.