Cat Calorie Calculator: How Much Should My Cat Eat?
Enter your cat's weight and life stage to get a starting estimate of daily calories, using the resting energy formula and life stage factors from the American Animal Hospital Association (AAHA). Add the calorie figure from your cat food label to see how many cups, cans or grams that is.
Checked against 4 sources· Not veterinary advice
How the calculator works
The calculator follows the two-step method in the 2021 AAHA Nutrition and Weight Management Guidelines:
- Resting energy requirement (RER) = 70 × (body weight in kg)0.75. This is the energy a cat uses at rest.
- Maintenance energy requirement (MER) = RER × a life stage factor. The factor accounts for neutering, growth, pregnancy, nursing and activity.
Worked example: a 10 lb cat weighs 4.54 kg. 70 × 4.540.75 = 218 kcal a day at rest. If the cat is a neutered adult, AAHA's factor is 1.2 to 1.4, so the estimate is 261 to 305 kcal a day.
The life stage factors
Where AAHA gives a range, the calculator shows a range. The Merck Veterinary Manual's table uses single values for some of the same groups, shown alongside for comparison.
| Cat | AAHA factor (× RER) | Merck factor (× RER) |
|---|---|---|
| Neutered or spayed adult | 1.2–1.4 | 1.2 |
| Intact (not neutered) adult | 1.4–1.6 | 1.4 |
| Inactive or prone to weight gain | 1.0 | 1.0 (obesity prone) |
| Weight loss (vet-supervised) | 0.8 | not listed |
| Growing kitten | 2.5 | 2.5 |
| Pregnant (gestation) | 1.6–2.0 | not listed |
| Nursing (lactation) | 2.0–6.0 | not listed |
AAHA's table has no separate factor for senior cats or for kittens of different ages, so the calculator does not invent one. For a senior cat, use the adult option that fits and track weight.
How to read the result
Treat the number as a first guess. AAHA describes these factors as general guidelines and says sedentary or indoor pets may need fewer calories, with intake adjusted by monitoring body weight and body condition score. If your cat gains weight on the estimate, feed less; if it loses weight it should not lose, feed more and talk to your vet.
Under AAFCO rules, cat food labels state calories per kilogram and per familiar unit such as a cup or a can, under the heading “Calorie Content”. Divide the daily calories by the figure per cup or can to get the amount. AAHA also recommends that treats and other extras make up no more than 10% of daily calories.
When to ask a vet
- Before starting a weight-loss plan: AAHA bases weight-loss calories on the ideal weight, which a vet should set.
- For a pregnant or nursing cat, where needs change week by week and with litter size.
- For any unexplained weight gain or loss, which AAHA says should prompt a fuller nutritional assessment.
- For cats with kidney disease, diabetes or other conditions that call for a therapeutic diet.
Frequently asked questions
How many calories should a cat eat a day?
It depends on weight and life stage. AAHA's method is resting energy (70 × weight in kg^0.75) times a life stage factor. A 10 lb (4.5 kg) neutered adult has a resting energy of about 218 kcal, so a starting point of about 261 to 305 kcal a day. Adjust from there using your cat's weight and body condition.
How much should an indoor cat eat?
AAHA notes that sedentary or indoor pets may need fewer calories than the standard factors suggest. For a cat that is inactive or gains weight easily, AAHA lists a factor of 1.0 × RER, the same as its resting energy.
How do I calculate my cat's RER?
Convert the weight to kilograms (pounds × 0.4536), raise it to the power 0.75, and multiply by 70. For a 4.5 kg cat: 4.5^0.75 is about 3.09, and 3.09 × 70 is about 216 kcal a day.
How many calories does a cat need to lose weight?
AAHA lists a weight-loss factor of 0.8 × RER and says to base the calculation on the cat's ideal weight, then adjust for the individual. Weight loss in cats should be planned and monitored with a vet.
How many calories does a kitten need?
Both AAHA and the Merck Veterinary Manual give a growth factor of 2.5 × RER for kittens. AAHA recommends feeding a growth diet until skeletal maturity, which for cats is typically about 1 year of age.
Do senior cats need fewer calories?
Not necessarily. AAHA's table has no separate senior factor, and the guidelines note that fat, protein and energy digestibility can fall in older cats, so energy intake can be higher for senior cats to make up for it. Weigh older cats regularly and ask your vet about any unexplained weight change.
Sources
- 2021 AAHA Nutrition and Weight Management Guidelines for Dogs and Cats, Box 1: Energy Requirement Calculations, American Animal Hospital Association (AAHA). Used for: RER = 70 × kg^0.75 and the feline life stage factors.
- 2021 AAHA Nutrition and Weight Management Guidelines for Dogs and Cats (J Am Anim Hosp Assoc 2021;57:153–174), American Animal Hospital Association (AAHA). Used for: Base weight-loss calculations on ideal weight; senior cats and digestibility; growth diets to about 1 year.
- Daily Maintenance Energy Requirements for Dogs and Cats (table), Merck Veterinary Manual. Used for: Cross-check of the cat factors (neutered 1.2, intact 1.4, obesity prone 1.0, kittens 2.5).
- Reading Labels, Association of American Feed Control Officials (AAFCO). Used for: Calorie content is stated per kilogram and per familiar unit (cup, can).