Pet calorie calculator — and an honest answer to “is my pet overweight?”

Veterinary teams start from Resting Energy Requirement (RER = 70 × body weight in kg to the 0.75 power) and multiply it by a life-stage factor. A neutered adult dog uses about 1.6 × RER and a neutered adult cat about 1.2 × RER. For example, a 66 lb (30 kg) neutered adult dog lands near 1,435 kcal per day, and a 10 lb (4.5 kg) neutered adult cat near 260 kcal per day. Your pet's real needs vary with health, body condition, and lifestyle, so treat any calculator result as a starting point to review with your vet.

Growing pets need far more energy per pound than adults, and the growth factors are published: puppies eat about 3 × RER until 4 months, then about 2 × RER until they reach adult size (2021 AAHA nutrition guidelines; Merck Veterinary Manual). Kittens run about 2.5 × RER, easing to 2 × RER as they approach adult weight (AAHA; Small Animal Clinical Nutrition, 5th ed.). Worked example: a 3-month-old, 10 lb (4.5 kg) puppy lands near 653 kcal per day, and a 6-month-old, 6 lb (2.7 kg) kitten near 297 kcal per day. Because they are growing, this calculator never applies weight-loss or weight-gain goals to a pet under 12 months — growth feeding is vet territory. Re-check every few weeks as weight climbs, feed a diet formulated for growth, and confirm the plan with your veterinarian.

Use the rib-and-waist check: at a healthy weight you can feel the ribs easily under a thin fat layer, and see a waist tuck behind the ribs from above. If ribs are hard to find or the waist has disappeared, your pet may be carrying extra weight; if ribs, spine, or hips are clearly visible, your pet may be underweight. A veterinarian confirms this with a hands-on body condition score (BCS), which is more reliable than weight alone.

The standard veterinary weight-loss approach feeds for the ideal weight, not the current one: about 1 × RER of ideal weight for dogs and 0.8 × RER of ideal weight for cats. When no vet-set goal exists yet, this calculator uses a provisional ideal about 10% below the current weight. Always confirm a weight-loss plan with your vet — cats in particular must never lose weight quickly, because rapid loss can trigger a dangerous liver condition.

Spayed and neutered pets typically burn fewer calories, so the standard factors drop — for dogs from about 1.8 × RER (intact) to 1.6 × RER, and for cats from about 1.4 × RER to 1.2 × RER. Feeding an altered pet like an intact one is a common, quiet cause of weight creep, which is why this calculator asks.

No. It is a free informational tool built on the widely used RER/MER framework. Nothing here is veterinary or medical advice, a diagnosis, or a treatment plan. Always consult a licensed veterinarian about your pet's weight, diet, and health, and never delay or disregard professional veterinary advice because of something you read here.