The feeding guide on a bag of pet food covers a wide range of animals, and many pets end up overweight following it. Veterinarians work out daily calories from body weight and life stage instead, and this calculator uses the same approach: a resting energy requirement (RER) multiplied by a factor that fits your dog or cat. Add your food’s calorie density and it converts the target into cups or cans.
How to use the pet calorie calculator
- Choose dog or cat and enter the current weight in pounds or kilograms.
- Pick the life stage and activity that fits: spayed or neutered adult, intact adult, inactive, weight loss, weight gain, working dog, puppy or kitten.
- For weight loss or gain, enter the ideal weight your veterinarian suggests; the calculation uses it instead of current weight.
- Optionally enter the calories per cup or can from the food label to see how much to feed.
- Read the daily calorie target, the RER behind it and the treat allowance.
Pet calorie formulas
These are the equations used in the AAHA nutrition and weight management guidelines and WSAVA nutrition toolkits. Some references use a linear shortcut, 30 × kg + 70, for pets between about 2 and 45 kg; the exponent form works across all sizes.
Common life-stage factors
| Dogs | × RER | Cats | × RER |
|---|---|---|---|
| Neutered adult | 1.6 | Neutered adult | 1.2 |
| Intact adult | 1.8 | Intact adult | 1.4 |
| Inactive or prone to gain | 1.2–1.4 | Inactive or prone to gain | 1.0 |
| Weight loss (ideal weight) | 1.0 | Weight loss (ideal weight) | 0.8 |
| Weight gain (ideal weight) | 1.2–1.8 | Weight gain (ideal weight) | 1.2–1.4 |
| Active or working | 2.0–5.0 | Growing kitten | 2.5 |
| Puppy under 4 months | 3.0 | ||
| Puppy 4 months to adult | 2.0 |
Worked example
A 50-lb spayed adult dog eating a kibble with 380 kcal per cup:
Weight: 50 lb ÷ 2.2046 = 22.68 kg
RER = 70 × 22.680.75 = 70 × 10.39 ≈ 727 kcal/day
MER = 727 × 1.6 ≈ 1,164 kcal/day → 1,164 ÷ 380 ≈ 3.1 cups a day, with up to about 116 kcal of that from treats.
A 10-lb neutered indoor cat works out to RER ≈ 218 kcal and MER ≈ 261 kcal a day.
Fine-tuning the amount
Use body condition, not just the scale
Factors are averages, and individual pets can need 20–30% more or less. Veterinarians judge body condition by feel: you should be able to feel the ribs under a thin layer of fat and see a waist from above. Weigh your pet every two to four weeks and adjust portions by about 10% at a time.
Count every calorie
Treats, chews, table scraps and food used for training all count. Keep them within about 10% of the daily total and cut the main meal to match.
Go slowly with cats
Cats that stop eating or lose weight too quickly can develop hepatic lipidosis, a serious liver condition. Feline weight loss should be gradual and planned with a veterinarian.
Pregnant and nursing animals, growing large-breed puppies and pets with kidney disease, diabetes or other conditions need diets designed by a veterinarian. To see how old your pet is in human terms, try the dog age calculator or cat age calculator, and switch units with the pounds to kilograms converter.
Frequently asked questions
What is RER?
Resting energy requirement is the energy a pet needs at rest in a comfortable environment, calculated as 70 times body weight in kilograms raised to the 0.75 power. It is the starting point for nearly all veterinary feeding calculations.
What is MER?
Maintenance energy requirement is RER multiplied by a factor for life stage and activity. A typical spayed or neutered adult dog needs about 1.6 × RER, and a neutered adult cat about 1.2 × RER.
How many calories should a dog eat to lose weight?
A common veterinary starting point is 1.0 × RER calculated at the dog's ideal weight, not its current weight. For cats it is about 0.8 × RER at ideal weight. Weight loss plans should be supervised by a veterinarian, especially for cats.
How do I convert calories to cups of food?
Find the calories per cup or per can on the food label, often listed as kcal/cup or kcal/can, and divide your pet's daily calories by that number. Use a real measuring cup or a kitchen scale, since scoops vary.
How many treats can my pet have?
Veterinary nutrition guidelines suggest treats make up no more than about 10% of daily calories. Reduce the main meals by the same amount so the total stays on target.