How many calories does an indoor cat actually need per day?

There is no single number, since it scales with body weight, but veterinary feline life-stage guidelines give a starting formula: resting energy requirement equals 30 times body weight in kilograms, plus 70. For a healthy young adult, that resting number is roughly what she needs in a day; an overweight, older or less active indoor cat typically needs less than that baseline, not the same amount. This matters more than it sounds like it should, since roughly half of cats seen at veterinary clinics today are overweight, largely from feeding by habit rather than by an actual calculation. Your vet can turn this formula into an exact daily number for your cat’s current weight and body condition.