How the pet calorie calculator works
Vets estimate a pet's daily calorie need in two steps. First comes the resting energy requirement (RER), the energy used at rest. It is then multiplied by a factor for life stage and activity to get the maintenance energy requirement (MER).
Daily calories = RER × multiplier
Typical multipliers from WSAVA and veterinary nutrition texts are 1.6 for a neutered adult dog, 1.8 intact, 1.0 for weight loss, 2 to 5 for working dogs and 3 for puppies under four months. For cats they are 1.2 neutered, 1.4 intact, 0.8 for weight loss and 2.5 for kittens. For weight loss, vets usually calculate RER from the target weight, not the current one.
Worked example
A neutered 50 lb (22.7 kg) dog has an RER of 70 × 22.70.75 ≈ 727 kcal. Multiplying by 1.6 gives about 1,164 kcal a day. A food with 380 kcal per cup means about 3 cups daily, including treats. A 10 lb neutered cat needs about 261 kcal a day (RER 218 × 1.2).
Frequently asked questions
How many calories does a dog need per day?
Roughly 30 kcal per pound for small dogs down to about 20 per pound for large dogs, but use the RER formula for a better estimate.
Why is the food bag amount higher?
Feeding guides are written for active, intact animals; most pets are neutered and less active.
How do I find calories in my pet food?
US labels list kcal per cup or per can in the calorie statement.
How fast should my pet lose weight?
About 1% to 2% of body weight a week for dogs and 0.5% to 1% for cats, under veterinary supervision.
Updated October 2026. Results are estimates for education, not financial or medical advice. All math runs in your browser; nothing you type is sent anywhere.