Pet calorie calculator
How much should I feed my cat?
Enter your cat’s weight and the calories printed on your food. You’ll get a daily starting point in cups or cans, worked out the way vets do it, with every step shown.
How this pet calorie calculator works
Vets start with your pet’s resting energy requirement (RER), the calories needed just to stay alive at rest: RER = 70 × weight^0.75, with weight in kilograms. Then they multiply it by a factor for life stage and lifestyle to get the maintenance energy requirement, the daily calories for a normal day.
We divide that by the calories printed on your food to get cups or cans. That’s it: no hidden adjustments, and every step is in “Show the math”.
| Pet and life stage | Factor × RER | Range vets use |
|---|---|---|
| Cat: Spayed or neutered adult | 1.2 | 1.2 |
| Cat: Intact adult | 1.4 | 1.4 |
| Cat: Inactive, or gains weight easily | 1.0 | 1.0 |
| Cat: Kitten (under 12 months) | 2.5 | 2–3, lower as they grow |
| Dog: Spayed or neutered adult | 1.6 | 1.6 |
| Dog: Intact adult | 1.8 | 1.8 |
| Dog: Inactive, or gains weight easily | 1.4 | 1.2–1.4 |
| Dog: Puppy under 4 months | 3.0 | 2–3 |
| Dog: Puppy 4 months to adult | 2.0 | 2–3, lower as they grow |
| Senior cat or dog | Adult factor | No separate factor published; see AAHA notes |
When to skip the calculator
Pregnant or nursing pets, pets on a weight-loss plan, pets recovering from illness or surgery, working dogs, and any pet with a medical condition or a vet diet need a number from your vet. Their needs swing too widely for one formula: nursing alone can run from 2 to 6 times RER.
Questions people ask
What does a pet calorie calculator do?
It estimates how many calories your cat or dog needs in a day from their weight and life stage, using the formula vets start with. This one then turns that number into cups or cans of your food, based on the calories printed on the label.
How many calories does a cat need a day?
A 10 lb spayed or neutered adult cat starts at about 260 kcal a day by the vet formula. Inactive cats or cats that gain weight easily start lower, and kittens need about twice as much per pound.
Is the feeding chart on the bag wrong?
Not wrong, but it’s a broad range for a typical pet. The Pet Nutrition Alliance calls package guidelines a starting point too, so use either one and adjust by your pet’s body condition.
Why does my food’s calories per cup matter so much?
Dry foods differ a lot in calories per cup, so the same scoop can mean very different amounts. Switching foods without checking can quietly add or remove calories every day.
Do senior pets need fewer calories?
Most senior dogs do. Cats are different: their needs tend to drop until about age 10 and then rise, and many older cats lose muscle, according to AAHA’s 2023 senior care guidelines. That’s why the calculator keeps the adult starting point and adds age-specific notes rather than one senior number.
How often should I recheck the amount?
Recheck whenever your pet’s weight, activity or food changes, and keep checking puppies and kittens as they grow. Your vet can tell you if your pet is at a healthy body condition.
Sources
- Pet Nutrition Alliance, Calculating Calories Based on Pet Needs (RER formula, factor ranges, the 50% note). Read October 27, 2026.
- Merck Veterinary Manual, Daily Maintenance Energy Requirements for Dogs and Cats (the factors we use). Read October 27, 2026.
- AAHA, 2023 Senior Care Guidelines for Dogs and Cats: Nutrition (how calorie needs change with age). Read October 27, 2026.