How many calories does a cat need?

A typical neutered adult cat needs about 1.2 × 70 × (weight in kg)^0.75 calories a day. For a 4 kg (9 lb) cat that is about 240 kcal; for a 5 kg (11 lb) cat, about 280 kcal. Intact cats need a little more, kittens much more, and cats that put weight on easily need less.

Here is how vets do the sum, the factor for each kind of cat, and how to tell whether the answer suits yours. If you want the number without the maths, use the cat calorie calculator.

Step 1: resting energy (RER)

Every calculation starts with the resting energy requirement: what your cat burns lying still in a comfortable room.

RER = 70 × (body weight in kg)^0.75

To do the power of 0.75 on a phone calculator, take the square root of the weight twice, then divide the original weight by that result. For a 4 kg cat: √√4 = 1.41, and 4 ÷ 1.41 = 2.83, so RER = 70 × 2.83 ≈ 200 kcal. Or just use the table below. Merck also gives a simpler straight-line version for pets between 2 and 45 kg, 30 × kg + 70, which gives similar answers in the normal cat range.

Use your cat’s ideal weight, not their current one, if they are overweight. Feeding an overweight cat for the weight they are now keeps them there.

Step 2: multiply by your cat’s factor

The neutered, intact, inactive and kitten figures are the Merck Veterinary Manual’s. The weight-loss figure is a common veterinary starting point drawn from the AAHA weight management guidelines; vets adjust it from there depending on progress.

Merck is clear that these are starting points: an individual cat can need up to 30% more or less than the formula predicts. Activity, coat, temperature, health and simple individuality all play a part.

Daily calories for cats, by weight

All figures are kcal a day, rounded. For the weight-loss column, use the cat’s target weight in the first column.

Kittens

Kittens need about 2.5 × RER at their current weight, which comes to roughly 175 kcal a day for a 1 kg kitten and 350 kcal for a 2 kg kitten. Merck notes kittens can also be fed kitten food free choice. Redo the sum as they grow, and move to adult food at around a year old. Neutering lowers energy needs, so many cats start gaining weight in the months after the operation; that is a good moment to recheck.

Senior cats

Older cats are less predictable than older dogs. The 2023 AAHA senior care guidelines note that published data on energy needs in ageing cats are extremely variable, and that in older cats protein is less digestible in about 20% of cats over 11 and fat in up to a third. So some seniors need fewer calories as they slow down, while others need more to hold their weight. Weigh a senior cat every month or two, and tell your vet about any unexplained weight loss: it can also be an early sign of illness such as an overactive thyroid, diabetes or kidney disease.

Step 3: turn calories into food

Find the calorie content on the label: dry food is usually given as kcal per kg, wet food as kcal per can or pouch.

• Dry: grams a day = daily kcal ÷ kcal per kg × 1,000
• Wet: pouches or cans a day = daily kcal ÷ kcal per pouch

A 4 kg neutered cat on dry food with 3,800 kcal/kg needs about 63 g a day. If you feed both wet and dry, split the calories between them first, then work out each portion. Feeding the full label amount of each is how many mixed-fed cats gain weight. Our guide to how much to feed a cat goes through wet, dry and meal timing.

Count the treats. Keep treats and extras to no more than about 10% of the day’s calories. For a 240 kcal cat that is only about 24 kcal, which a few commercial treats can use up.

Step 4: check the number against your cat

The formula gets you close. Your cat’s body confirms it.

• Ribs: easy to feel under a light layer of fat, but not visible.
• Waist: a gentle narrowing behind the ribs when you look from above.
• Belly: only a small fat pad underneath when you look from the side.
• Weight: check every two to four weeks while you are adjusting, then monthly.

If your cat gains weight over two weigh-ins in a row, reduce the daily amount by about 10% and check again in a few weeks. If they lose weight you didn’t intend, increase it and talk to your vet.

Never cut a cat’s food drastically. A cat that eats very little for even a few days, especially an overweight one, risks a serious liver condition called hepatic lipidosis. Any weight loss should be slow and planned with your vet. If your cat stops eating for more than a day, call your vet. See how to help your cat lose weight for a safe plan.

How the calculator handles it

The cat calorie calculator asks for your cat’s weight, age and how active they are, and uses the same resting-energy formula. Treat its answer, like any formula, as a starting figure you then fine-tune by weighing your cat.

In PetTrackr, your cat’s daily target is worked out from their weight and age (or set to the number your vet gave you), each logged meal fills the day’s calorie ring, and every weigh-in is placed against the healthy range for their breed, age and sex.