Cat Calorie Calculator

Resting Energy Requirement (RER) estimates calories used at rest. The calculator uses RER = 70 x BW_kg^0.75. Its daily energy estimate multiplies RER by a life-stage and activity factor: 0.9 to 1.6 for adults, up to 3.0 for kittens, and 2.5 to 4.0 for lactating cats. Treat the output as a starting estimate and confirm an individual feeding plan with a veterinarian.

Vets use a 9-point Body Condition Score (BCS). The ideal range is 4 to 5 of 9, which means the ribs are easy to feel under a thin layer of fat (think the back of your hand, not a knuckle), the waist is visible from above, and there is a slight abdominal tuck behind the ribcage when viewed from the side. BCS 1 to 3 is underweight, with ribs and spine visible and no body fat. BCS 6 to 7 is overweight, with ribs hard to feel and no waist. BCS 8 to 9 is obese: heavy fat pads on the back, no waist, distended belly, and a real risk for diabetes mellitus and hepatic lipidosis. The calculator flags BCS 1 to 3 and 8 to 9 for a vet consult.

Energy needs can change after spaying or neutering, but the size of the change varies by cat. In this calculator, a spayed or neutered adult with low indoor activity uses 0.9 x RER, while an intact adult at the same activity level uses 1.2 x RER. Monitor weight and body condition with a veterinarian instead of assuming one adjustment fits every cat.

Cats are built for many small meals. Free-living cats hunt 10 to 20 small prey items a day, each around 30 kcal, so the natural pattern is little and often. At home, 4 small meals for kittens, 3 for seniors, and 2 to 3 for healthy adults is closer to that pattern than the once-a-day bowl most people default to. If you cannot offer multiple meals manually, a timed feeder splits the daily ration into 3 to 5 portions and removes the begging-when-bored problem. Free feeding dry food is the single biggest contributor to indoor-cat obesity, because most cats overshoot their MER by 30 to 50 percent when food is always available.

Call the vet if you see rapid weight loss of more than 10 percent over a few weeks (a 10 lb cat losing more than 1 lb), if BCS hits 1 to 3 or 8 to 9 of 9, or if a pregnant or lactating queen is losing condition despite eating to appetite. Sudden weight loss in a cat is often the first sign of hyperthyroidism, kidney disease, diabetes, or GI cancer, all of which respond much better to early treatment. Anorexia of more than 24 to 48 hours in an overweight cat is a true emergency: cats are prone to hepatic lipidosis (fatty liver) when they stop eating, and that condition is life-threatening. The calculator's vet-consult flag fires for kittens, pregnancy, lactation, and extreme BCS to keep these cases in front of a professional rather than buried in a portion table.