Cats are efficient eaters with a lower energy need than their size might suggest — which is why so many are overfed. This calculator derives a precise daily kcal target from weight and life stage.
A feline RER
Like dogs, cats start from RER ≈ 70 × kg^0.75, but several life stages carry their own multipliers — kittens need ~2.5× for growth, queens up to 2× while lactating, and weight-loss plans 1.0×.
The overfeeding trap
A cat's daily need is modest and its food is energy-dense, so free-feeding creeps calories up quickly. Portioning to a fixed kcal target — instead of eyeballing — is the strongest lever against feline obesity.
Frequently asked questions
A 4.5 kg neutered adult cat needs about 250–280 kcal/day, split across two meals. Multiply RER by life stage to match your cat.
Cats have a genuinely lower RER coefficient than dogs per kg — their resting needs run about 70 × kg^0.75, feeding a compact, efficient metabolism.
Yes, if rapid. Cats can develop hepatic lipidosis when starved, so weight loss should be slow and supervised by a vet — a crash diet is the risky path.