Cat calorie calculator

Every number on this page is built from a body weight. For a cat at a healthy weight that works. For an overweight cat it is a trap: type in today’s heavier weight and you get the calories that keep your cat that heavy. AAHA (2021) says weight-loss calculations should be based on ideal weight, and FEDIAF (2025) says the same: energy needs should be based on optimal body weight.

For cats the reverse mistake is also dangerous: cutting food hard to “fix” the weight. Read the section on weight loss below before you change anything.

There are three published ways to work out a cat’s energy, and they give different answers. We use the first and show the others as cross-checks.

1. Resting energy × a life-stage factor (AAHA 2021, Merck Veterinary Manual). RER = 70 × (weight in kg)^0.75, then kcal a day = RER × factor. It is the same method as our dog calculator, and the basis of AAHA’s weight-loss plan.
2. NRC (2006), used for the WSAVA chart. 100 × BW^0.67 for a lean adult cat and 130 × BW^0.4 for an obese-prone one. The exponent is 0.67, not 0.75.
3. FEDIAF (2025). 100 × BW^0.67 for active cats and 75 × BW^0.67 for neutered or indoor cats (a range of 52 to 75). FEDIAF notes that cats vary little in adult size, so their needs are often given per kg of body weight, and that if metabolic weight is used, 0.67 is more accurate for cats than 0.75.

Then the calories are turned into grams: grams = kcal ÷ (kcal per kg of the food) × 1,000. If your label gives kcal per 100 g, multiply by 10 to get kcal per kg. Each figure is rounded to a whole number and grams are worked out from the kcal shown, so you can repeat the sums and get the same answer.

Is 70 × BW^0.75 the same as 30 × BW + 70?

No. 30 × BW + 70 is a straight-line shortcut that the Merck Veterinary Manual limits to animals above 2 kg and below 45 kg. For a 4 kg cat the two are close (190 against 198 kcal), but kittens are often under 2 kg, and there the shortcut overestimates: at 1.36 kg it gives 111 kcal against 88. This calculator always uses 70 × BW^0.75, which works at any weight.

The same calories become very different amounts of food. A 4 kg neutered cat on 238 kcal needs 63 g of a dry food at 3,800 kcal per kg, but 238 g of a wet food at 1,000. Typical ranges, for guidance only: dry food about 3,200 to 4,200 kcal per kg, canned or pouch about 700 to 1,300. We do not quote values for named brands. Read the energy from your own food’s label.

Kittens, by weight

Kittens need far more energy for their size than adult cats. AAHA (2021) and the Merck Veterinary Manual give 2.5 × resting energy for a kitten. Hand et al. (Small Animal Clinical Nutrition, chapter 24) use 2.5 × for kittens under 6 months and 2 × from 6 months until adulthood, which is what this calculator does. FEDIAF (2025, Table VII-10) is similar: 2.0 to 2.5 times adult maintenance up to 4 months, 1.75 to 2.0 from 4 to 9 months, and 1.5 from 9 to 12 months.

The NRC (2006) also gives a kitten growth equation. This calculator uses the simpler factors above, which are published in AAHA, Merck and Hand et al.

• Weigh your kitten every week. Healthy kittens gain about 100 g a week until about 20 weeks of age, reach about 80% of adult size at 30 weeks and adult weight at about 40 weeks (Hand et al.). If your kitten is not gaining, feed a little more and tell your vet.
• Meals: 3 to 4 a day under 6 months, and most kittens cope with 2 by 6 months. Merck notes kittens can be fed free-choice; Hand et al. say that is best kept to kittens under about 5 months, and unsuitable for a kitten that is already overweight.
• Feed a complete food made for kittens, and never put a kitten on a diet. Neutering lowers energy needs, so watch the weight after surgery.

• The amount: 0.8 × the resting energy of the target weight (AAHA 2021). Merck gives another way to start: 70% of maintenance energy. For the 6 kg cat above, that is 173 kcal a day.
• The speed: a reasonable goal is about 1% of body weight a week (Merck). For the 6 kg cat aiming for 4.5 kg that is roughly 29 weeks, about 7 months. Faster is not better.
• The checks: weigh every 2 weeks (Merck), and keep your vet in the loop. Your vet decides whether any tests are needed during the plan.
• The food: AAHA recommends a therapeutic weight-loss diet when calories are cut to RER or below, because these foods are fortified to avoid nutrient shortages, and notes that high-moisture (wet) foods may increase fullness in cats. Do not simply feed less of an ordinary food.
• Cross-check: AAHA reports that cats on weight-loss programmes ate an average of 52 kcal per kg^0.711 a day. For a 4.5 kg target that is about 152 kcal; our figure is 14% higher.

Older cats

Do not put an older cat on a diet yourself. Weight loss is common in very old cats and is often a sign of illness (Hand et al.: underweight becomes much more common after 11 years). AAHA notes that older cats can digest food less well and may need more calories, not fewer. Hand et al. give 1.1 to 1.4 × resting energy for healthy mature adult cats, and up to 1.6 for active or underweight ones. This calculator treats a senior cat like an adult and tells you to see your vet about any weight change.

We found little firm guidance that either is better for every cat, so we say only what the sources say:

• AAHA (2021): high-moisture diets may increase fullness in cats and help weight loss.
• Hand et al. (kittens): dry foods carry more energy per volume, which helps small kittens with high calorie needs; moist foods tend to be more palatable. Both are suitable for weaned kittens.
• Whichever you use, it should say on the label that it is complete and balanced for your cat’s life stage, and it should be weighed. A cup of dry food and a cup of wet food are not the same calories.

If you feed both, decide what share of the calories each gives, then divide that share by each food’s own kcal per kg. Add the grams. Do not just add both full amounts.

Never feed a cat a vegetarian or vegan diet. Cats cannot make enough of several nutrients themselves and get them from animal tissue:

• Taurine. FEDIAF (2025) calls taurine an essential nutrient for the cat; a shortage can cause damage to the retina (central retinal degeneration), heart muscle disease (dilated cardiomyopathy) and failure to reproduce. The Merck Veterinary Manual says cats must have some animal-based protein because plant protein contains no taurine.
• Preformed vitamin A. Cats cannot make it from the carotene in plants (Merck).
• Arachidonic acid. Unlike dogs, cats cannot readily convert plant linoleic acid into it (Merck).

The bulk of a cat’s food must be a complete, meat-based cat food. Merck notes that cats develop deficiencies when fed diets made for dogs, and the same applies to vegetarian diets.

The 9-point body condition score (BCS) from the WSAVA and FEDIAF guidelines tells you whether the weight is healthy. The aim for most cats is 4 to 5 out of 9, and FEDIAF notes that 4 may suit a neutered, inactive cat better than 5.

To estimate a healthy weight, divide today’s weight by (1 + the percentage over). A 6 kg cat scoring 7 is about 20 to 30% over ideal, so its healthy weight is roughly 4.6 to 5 kg. The calculator above does this for scores 6 to 8. Compare your cat with the pictures on the WSAVA body condition chart for cats.

An adult cat

Mittu is a neutered 4 kg tabby, a healthy shape (BCS 5), indoors with some play. Her food is a dry food printed at 3,800 kcal per kg. She is fed 3 meals a day.

1. Resting energy: 70 x 4^0.75 = 198 kcal
2. Daily energy: 198 x 1.2 = 238 kcal
3. Food: 238 kcal / 3,800 kcal per kg x 1,000 = 63 g a day
4. Per meal: 63 g / 3 meals = 21 g

So Mittu eats about 63 g of dry food a day, 21 g a meal. If she is mostly asleep and gains weight easily, choose “Quiet indoor”: 1.0 × 198 gives 198 kcal, about 52 g. After two weeks she is weighed again. If she is unchanged and her ribs are still easy to feel, the number is right.

A kitten

Chhotu is a 3-month-old kitten weighing 1.5 kg, on a kitten food of 4,000 kcal per kg, in 4 meals a day. Under 6 months the factor is 2.5.

1. Resting energy: 70 x 1.5^0.75 = 95 kcal
2. Daily energy: 95 x 2.5 = 238 kcal
3. Food: 238 kcal / 4,000 kcal per kg x 1,000 = 60 g a day
4. Per meal: 60 g / 4 meals = 15 g

That is about 60 g a day, 15 g a meal. Hand et al.’s table for a 3-month-old gives about 300 kcal for this weight, so if Chhotu gains less than about 100 g a week, feed a little more.

For a neutered adult at normal activity, here are the three published figures side by side. WSAVA’s one-page chart is for a healthy cat in ideal body condition and is built from the NRC equations. FEDIAF’s indoor range is 52 to 75 × BW^0.67 and its active figure 100 × BW^0.67.

So the three standards do not agree closely for cats: for a 4 kg cat they range from about 130 to about 255 kcal. The safest reading is that the answer is a range, and your own cat sits somewhere in it. If your cat is neutered and indoors, quiet and gains weight easily, choose “Quiet indoor”. At 4 kg that is 198 kcal, within about 4% of FEDIAF’s 190. WSAVA’s 2011 assessment guidelines say energy needs can differ from a formula by up to 50% either way in cats, which is why weighing matters more than the formula.

A factor of 1.2 means “20% more than resting”. It is an average across many cats, not a measurement of yours.

1. Feed the calculated amount, weighed on kitchen scales, for 2 to 4 weeks. Count every treat and lick of cream.
2. Weigh your cat every 2 weeks, on the same scale at the same time. A cat is small: 100 g is 2.5% of a 4 kg cat, so a baby scale that reads to 10 g is better than a bathroom scale.
3. Feel the ribs. If the weight is creeping up or the ribs are getting hard to feel, reduce the food by about 10%. If your cat is losing weight when you did not intend it, do not simply feed more: see your vet. Change in steps of about 10%, and re-check after another 2 weeks.
4. Treats, chews and anything given for medicine should stay under 10% of daily calories and come out of the meals.

• Kittens under 8 weeks and orphan kittens. Their feeding is on a plan from your vet.
• Pregnant or nursing queens. Needs rise a lot (AAHA 2021 gives 1.6 to 2.0 times resting in pregnancy and 2.0 to 6.0 in nursing). Ask your vet.
• Sick cats: kidney disease, an overactive thyroid, diabetes, liver, heart and gut disease, cancer, dental pain and many others change the calorie target and the right food. If your cat has a diagnosed illness, is on a prescription diet or is losing weight without a diet, follow your vet.
• Very small or very large cats. Below about 4 kg the factor method gives lower figures than WSAVA’s chart. Large breeds such as the Maine Coon should be judged by body condition.
• Home-cooked or raw diets. The calculator only gives calories. AAHA (2021) notes that most published home-cooked recipes, even those written by vets, are not complete and balanced. Cats need nutrients such as taurine that are easy to miss in a home recipe.

Related: dog calorie calculator · puppy food calculator · all diet charts.