How this calorie calculator works
RER = 70 × (weight in kg)0.75 is the standard veterinary formula for resting energy, valid at any body weight. MER = RER × multiplier, where the multiplier depends on life stage and reproductive status — from 1.0× for a cat prone to weight gain up to 3× for a puppy under 4 months old.
Sources
RER formula and the full MER multiplier table (life stage / status × RER): Merck Veterinary Manual, "Nutritional Requirements of Small Animals", the standard veterinary reference, itself drawn from the National Research Council's Nutrient Requirements of Dogs and Cats (2006). Fetched September 18, 2026.
Questions
What is RER and MER?
RER (Resting Energy Requirement) is the calories a pet burns at complete rest — base metabolism only. MER (Maintenance Energy Requirement) multiplies RER by a life-stage and activity factor to estimate typical daily need.
Why does neutering lower the calorie estimate?
Neutered pets tend to run a lower metabolic rate, so veterinary references use a smaller multiplier — 1.6× RER for dogs and 1.2× for cats — than for intact adults, at 1.8× and 1.4×.
How much food is that in cups?
Enter your food's energy density (kcal per cup — check the bag or the manufacturer's site for "metabolizable energy" or "kcal/cup") and the calculator divides your daily calories by it.
Should I trust this over my vet or the bag's feeding chart?
Use it as a starting point, not a prescription. Bag feeding charts often run high because they assume an average, unneutered, moderately active pet — actual needs vary a good deal between individuals at the same weight. Weigh your pet periodically and adjust the amount you feed.
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