How much should I feed my cat to gain weight?

On the clinical weight-gain factor — 1.3× the resting energy of the target weight — a 4 kg cat aiming for 4.5 kg needs about 281 kcal a day: roughly 0.74 cups of a 380 kcal/cup food, or 81 g, split across two or three meals. The same cat aiming for 5.5 kg needs about 327 kcal, about 0.86 cups. But first: a cat that is losing weight while eating normally needs a veterinarian, not more food.

Part of our feeding guides index — every calculator and chart on the site in one place.

In cats, unexplained weight loss is a medical finding, not a feeding problem. Hyperthyroidism, chronic kidney disease, diabetes and dental pain all show up as a cat that eats and still shrinks. The calculation below is for a cat that has already been assessed and needs a measured gain plan — where the reason for the loss is known and the only thing left to fix is the amount.

Daily amount, by target weight

Adult, neutered, typical indoor activity, on a 380 kcal/cup food. Find your cat's current weight, then read across to the weight you are feeding for:

For comparison, the same cats eating to maintain their current weight (1.2×): 3 kg 191 kcal (0.50 cups) · 4 kg 238 kcal (0.63 cups) · 5 kg 281 kcal (0.74 cups) · 6 kg 322 kcal (0.85 cups). The gain plan above runs about 15 to 22% higher than those figures. Cup weights assume 110 g per cup; cat food varies more than dog food, so use your own bag's figure if it states one. Every number is produced by the same engine that runs the calculator above.

Where this factor comes from — and what it is not

The 1.3× figure is clinical practice, not a published standard. Clinical and educational veterinary sources give a range of roughly 1.2 to 1.8 times the resting energy of the target weight for weight-gain feeding; for cats the commonly quoted band is narrower, around 1.2 to 1.4, and this page uses 1.3. It is not a row in the NRC 2006 maintenance table: that table lists weight loss, neutered adults, intact adults, activity levels, growth, senior, pregnancy and lactation, but it has no weight-gain row. The RER equation below is a published standard; the gain factor is not, and this page keeps the two separate.

⚠ Note the cat figures are not simply a smaller version of the dog ones. A cat's maintenance need (1.2) is lower than a dog's (1.6), so the gain factor sits closer to maintenance than it does for dogs — which is why the increase here is about 15 to 22% rather than the ~29–33% a dog plan produces.

Recalculate every one to two weeks

The target moves as the cat gains. A 4 kg cat aiming for 4.5 kg is a 4.5 kg cat once it gets there, and from that point the maintenance amount applies instead. Clinical guidance for weight-gain feeding is generally to recheck every one to two weeks, because a cat is small enough that a small daily surplus adds up quickly.

🔴 If your cat stops eating, that is urgent

A cat that stops eating is not the same as a dog that skips a meal. Cats can develop hepatic lipidosis (fatty liver) when they do not eat, which is serious and can be fatal. Contact a veterinarian the same day a cat has not eaten for 24 hours. At 48 hours, or if there is vomiting, lethargy, or yellowing of the gums and skin, treat it as an emergency.

This is also why never withhold food from a cat as a diet method. If your cat refuses the increased amount, that is a reason to speak to a vet, not to wait it out.

How fast is safe

Gain for a cat is planned slowly and, ideally, with a veterinarian involved — the amount above is a starting point to be adjusted from the trend, not a target to force. Weigh the cat on the same scale at the same time of day, and change the amount by a small percentage rather than in one jump. If the cat is gaining faster than expected, reduce rather than continue.

Where these numbers come from

Three steps, and the first two have different status:

1. Resting energy of the target weight — RER = 70 × kg0.75, the NRC energy equation. Note it is the target weight, not the current one.
2. Weight-gain factor × 1.3 — clinical practice (see above), not an NRC table row.
3. Divide by the food — daily calories ÷ kcal per cup = cups per day.

The factor tables, with their sources, are published in the open reference dataset (CC BY 4.0), so any number on this page can be re-computed independently. Our full method is on how we check our numbers.

Not for a kitten

Growing kittens should not be on a weight-gain plan. They are supposed to be gaining weight, and their amounts come from growth schedules rather than a gain target, so the calculator above declines anything under twelve months. For a kitten, use the kitten feeding schedule by age or how much to feed a kitten instead.

When the weight loss is the real problem

Most underweight cats are not underfed. An older cat that is hungry and still losing weight is the classic picture of hyperthyroidism; weight loss is also a common sign of chronic kidney disease, diabetes, dental pain and chronic intestinal disease. Pain, parasites and a diet that does not suit the cat do the same. Unexplained weight loss is a veterinary question before it is a feeding question. Once a veterinarian has assessed the cat and the cause is known, the calculation above gives you a measured plan to work from. For a cat that is thin and eating normally, feeding more usually just adds calories to an untreated problem.

Common follow-up questions

Do I just switch to a higher-calorie food? It is one lever, not the whole plan. A denser food means fewer cups for the same calories, which matters for a cat with a small stomach — but the daily calorie target still comes from the calculation above, and switching food without re-reading the label changes the amount even when the scoop does not.

How much more is this than normal? About 15 to 22% more than feeding the same cat to maintain its current weight. Part of that comes from calculating at the heavier target weight, and part from the slightly higher factor. For cats the gap above maintenance is smaller than it is for dogs, because a cat's maintenance factor starts lower.

Do treats count? Yes — and for a small cat they count quickly. Treats come out of the daily total, not on top of it; keep them under about a tenth of the day's calories. The cat treat calculator works the limit out by weight.

What about wet food? Wet food is mostly water, so it cannot be swapped cup for cup with dry. Convert it on calories rather than volume — see how much wet food to feed a cat and the wet to dry conversion page.

Sources: the energy equation follows the National Research Council’s Nutrient Requirements of Dogs and Cats (2006); the weight-gain factor is clinical practice (see above) and is not part of that table. Body condition framing follows the WSAVA Global Nutrition Committee guidelines. This page is general information, not veterinary advice.

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