Pet food bags tell you how many calories to feed, but the right number for your pet starts with their weight and life stage — and it's a number that changes as they do.
The RER baseline
The resting energy requirement is the calories burned doing nothing — the metabolic floor. Its sub-linear scaling with weight (70 × kg^0.75) is why a 40 kg dog doesn't need twice the calories of a 20 kg dog.
Life stage multipliers
Neutering lowers needs, growth and reproduction raise them, and weight-loss goals cut them. Applying the right multiplier to RER turns a floor into a daily target.
Where the number breaks down
Multipliers are averages. A lazy greyhound and a hyperactive spaniel at the same weight won't need identical calories. Weighing monthly and adjusting by body condition keeps the estimate honest.
Frequently asked questions
Resting energy requirement ≈ 70 × weight^0.75. It's the baseline calories a pet burns at rest, before activity and life stage are factored in.
A 20 kg neutered adult dog needs roughly 1,050 kcal/day. Intact or more active dogs need more, and weight-loss plans less.
A 4 kg neutered adult cat needs about 240 kcal/day — typically split across two meals.