Daily Calorie Needs Calculator (RER / MER)
Turn your pet’s weight and life stage into a daily calorie target using the same RER and MER formulas vets and nutritionists rely on.
Calories are the number behind healthy weight
More than half of dogs and cats in many countries are overweight, and it almost always starts with feeding by the scoop rather than by need. The RER formula gives a sound biological baseline; the MER factor tailors it to whether your pet is a couch companion, a working athlete, or a growing youngster.
Pair the calorie target with the food-portion calculator to turn it into cups or grams of your specific food, and re-check every few weeks against your pet’s body condition rather than the number on the bag.
Frequently Asked Questions
What are RER and MER?
RER, the Resting Energy Requirement, is the energy a resting animal burns just to stay alive. It's calculated as 70 × (body weight in kg)^0.75. MER, the Maintenance Energy Requirement, is RER multiplied by a factor for life stage and activity — the everyday calorie target you actually feed to.
Which activity factor should I choose?
Common multipliers are about 1.0 for weight loss, 1.4 for an inactive senior, 1.6 for a neutered adult, 1.8 for an intact adult, 2.0 for an active adult, and up to 3.0 for a growing puppy or a hard-working dog; kittens sit around 2.5. Pick the one that best matches your pet today, and adjust as their weight and condition change.
Do I weigh my pet in kilograms or pounds?
Either — the tool converts pounds to kilograms for you before applying the formula. Use the most accurate current weight you have; a scale at home or at the vet is far better than a guess, because the ^0.75 curve means small errors in weight shift the calorie target.
Is this the exact amount my pet should eat?
No — it's a starting point. Two pets of the same weight can differ by 25% or more in real needs depending on metabolism, breed, spay/neuter status, and environment. Feed to body condition: if your pet is gaining or losing weight you don't want, adjust the amount and re-check in a few weeks.
Can I use this for weight loss?
You can use the weight-loss factor to get a conservative starting figure, but a real slimming plan should be built around your pet's target (ideal) weight and monitored by your vet. Cats especially must never be crash-dieted — losing weight too fast can cause a serious liver condition. Always plan weight loss with professional guidance.
Educational estimate only — not veterinary advice. Individual needs vary; confirm feeding amounts and any weight plan with your vet.