How much to feed a cat: the formula vets use
Veterinarians estimate a cat's energy needs the same way as a dog's, in two steps. First the resting energy requirement (RER), the calories a cat burns at rest:
RER (kcal/day) = 70 × (body weight in kg)0.75
Then RER is multiplied by a factor for life stage, giving the maintenance energy requirement, the calories your cat needs per day:
| Situation | Factor × RER |
|---|---|
| Kitten | 2.5 |
| Spayed or neutered adult | 1.2 |
| Intact adult | 1.4 |
| Inactive adult or prone to weight gain | 1.0 |
| Weight loss (based on ideal weight) | 0.8 |
Divide the daily calories by the calorie content of your food. In the US, cat food labels must list calories as kcal per kg, and many also give kcal per cup or per can.
Example: a spayed 10 lb (4.5 kg) adult cat. RER = 70 × 4.50.75 ≈ 218 kcal. Daily need = 218 × 1.2 ≈ 261 kcal. With a dry food of 400 kcal per cup, that is about 0.65 cups a day, roughly two thirds of a cup. If half the calories come from wet food with 90 kcal per 3 oz can, the cat gets about 1.45 cans plus 0.33 cups of dry food a day.
Cat feeding chart by weight
Daily calories for healthy adult cats. The cups column assumes a dry food with 400 kcal per cup; check your own bag and use the calculator for an exact amount.
| Cat weight | Inactive | Spayed / neutered | Intact | Cups/day (neutered) |
|---|---|---|---|---|
| 4 lb (1.8 kg) | 109 kcal | 131 kcal | 153 kcal | 0.33 |
| 6 lb (2.7 kg) | 148 kcal | 178 kcal | 208 kcal | 0.44 |
| 8 lb (3.6 kg) | 184 kcal | 221 kcal | 258 kcal | 0.55 |
| 10 lb (4.5 kg) | 218 kcal | 261 kcal | 305 kcal | 0.65 |
| 12 lb (5.4 kg) | 249 kcal | 299 kcal | 349 kcal | 0.75 |
| 14 lb (6.4 kg) | 280 kcal | 336 kcal | 392 kcal | 0.84 |
| 16 lb (7.3 kg) | 310 kcal | 371 kcal | 433 kcal | 0.93 |
| 18 lb (8.2 kg) | 338 kcal | 406 kcal | 473 kcal | 1.01 |
For an overweight cat, do not use its current weight from this chart. Use the "needs to lose weight" option with the ideal weight your vet recommends.
Wet food, dry food or both?
Both can be complete diets. Wet food has much more water and fewer calories per bite, which helps some cats drink more and feel full. Dry food is calorie-dense and easy to over-feed, so measure it with a real measuring cup or, better, a kitchen scale. Many owners feed both. The key is to split the calories, not the volume: when you add a can of wet food, take the matching calories out of the dry food. The calculator does this for you with the "What do you feed?" setting.
How much to feed a kitten
Kittens need about 2.5 times their resting energy, far more per pound than adults, and they eat best in three to four small meals a day. Feed a food labeled for growth or for all life stages, weigh your kitten every one to two weeks and recalculate. Most cats reach adult size around 12 months; switch to the adult setting then, and lower the amount after spaying or neutering, when energy needs drop.
Adjusting the amount
Any calculator gives a starting point. Weigh your cat every few weeks and check body condition: you should feel the ribs under a thin layer of fat and see a slight waist from above. If your cat gains, reduce the daily amount by about 10%; if it loses weight it should not, add 10%. Treats should stay under 10% of daily calories.
Cats should lose weight slowly, about 0.5–2% of body weight per week. Never put a cat on a crash diet: a cat that stops eating for a few days can develop hepatic lipidosis (fatty liver disease), which is life-threatening. A sudden change in appetite or weight in an older cat is a reason to see the vet; our guide on when a cat is considered senior covers the signs of aging to watch for.
Frequently asked questions
How many calories does a cat need per day?
Start with the resting energy requirement, RER = 70 × (body weight in kg)^0.75, and multiply it by a life-stage factor: 1.2 for a spayed or neutered adult, 1.4 for an intact adult, 1.0 for an inactive cat that gains weight easily and 2.5 for a kitten. A spayed or neutered 10 lb (4.5 kg) adult cat needs about 260 kcal a day.
How much dry food should I feed my cat?
Divide your cat's daily calories by the calories per cup on the food bag. Dry cat foods vary a lot, so check the label. A spayed or neutered 10 lb cat that needs about 260 kcal a day gets about two thirds of a cup of a food with 400 kcal per cup.
How many cans of wet food should a cat eat a day?
Divide the daily calories by the calories per can on the label. A 3 oz can often has around 70 to 100 kcal, so a 10 lb neutered cat on wet food only may need about three 3 oz cans a day. Check your brand, because calories per can differ widely.
How do I mix wet and dry cat food?
Decide what share of the daily calories should come from each food, for example half and half. Work out the calories for each part and convert them with the calories per cup and per can. Reduce the dry food when you add wet food, so the total calories stay the same.
How often should I feed my cat?
Most adult cats do well on two or more measured meals a day. Kittens need three to four meals. Measuring the daily amount and splitting it into small meals, or using a food puzzle, helps prevent weight gain compared with leaving the bowl full all day.
Sources
- Merck Veterinary Manual: Daily Maintenance Energy Requirements for Dogs and Cats (energy factors for cats).
- AAHA Nutrition and Weight Management Guidelines for Dogs and Cats (2021): weight loss in cats.
- WSAVA Global Nutrition Committee: nutritional assessment guidelines and body condition score charts.
- AAFCO: calorie content statements on pet food labels.
This calculator gives an estimate for healthy cats, for general information. It is not veterinary advice. Cats with medical conditions, pregnant or nursing cats and cats on a weight loss plan should be fed as your veterinarian advises. Last updated: October 2026.