Tool
Cat food calculator (calories per day)
Calculate nowQuick answer
For cats the math starts with resting energy, RER = 70 × (body weight in kg)^0.75 kcal per day, multiplied by a factor from the Merck Veterinary Manual: 1.2 for a spayed or neutered adult, 1.4 for an intact adult, 1 for a cat prone to weight gain and 2.5 for kittens. Divide by the kcal/kg on the label to get grams. Indoor neutered cats need little more than resting energy, which is why they gain weight so easily.
Guide · $9The Dog and Cat Food GuideHow the math works
The tool converts pounds to kilograms and uses the Merck Veterinary Manual formula, RER = 70 × (kg)0.75, then the cat factor:
| Situation | Factor |
|---|---|
| Kitten | 2.5 × RER |
| Adult, intact | 1.4 × RER |
| Adult, spayed or neutered | 1.2 × RER |
| Adult, prone to weight gain | 1 × RER |
Daily kcal ÷ kcal/kg on the label × 1,000 gives grams; the tool also shows ounces. Kittens can alternatively be fed free choice, per Merck.
Limits
These are averages built on the National Research Council’s nutrient profiles. Treats count toward the total. Check body condition every few weeks, following the WSAVA nutrition guidelines, and ask your veterinarian for pregnant, nursing, sick or overweight cats.
Frequently asked questions
Why is the cat factor lower than the dog factor?
Cats spend less energy above rest. A neutered indoor cat sits around 1.2 times resting energy, while a neutered dog sits at 1.6. Using dog math on a cat overestimates food by about a third.
Should I mix wet and dry food?
You can, but count both. Work out the daily calories here, subtract what the wet food provides (from its kcal per can) and give the rest as dry food.
How fast should an overweight cat lose weight?
Slowly and under veterinary care. Merck suggests starting at about 70% of maintenance energy for cats. Cats that stop eating can develop serious liver disease, so never cut food drastically.
Sources
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