How much to feed a cat: wet, dry and mixed feeding

Step 1: a cat’s daily calories, with cat factors

Every method starts from the resting energy requirement (RER), the energy a fed cat uses at rest in a comfortable room. Both AAHA and the Merck Veterinary Manual give it as 70 × (body weight in kg)^0.75 kcal a day. A kcal (kilocalorie) is the “Calorie” printed on labels.

Daily need, the maintenance energy requirement (MER), is RER times a life-stage factor. Cats have their own factors, and they are lower than dogs’:

For the house example, a neutered 9.9-lb (4.5-kg) cat, RER is 216 kcal. AAHA’s range for neutered cats gives 260–303 kcal, and our calculator uses the middle, about 281 kcal a day. The National Research Council’s owner brochure lands in the same place: it lists 280 kcal a day for a lean 10-lb cat and 240 for an overweight one. The World Small Animal Veterinary Association (WSAVA) chart of adult cat calories is built from those same NRC formulas.

Some online calculators apply dog factors to cats. The middle of AAHA’s neutered-dog range, 1.5, applied to the same 4.5-kg cat gives about 324 kcal, 15% more than the cat figure of 281.

Two groups need a different approach:

• Kittens: 2.5 × RER, so a 4.4-lb (2-kg) kitten starts near 294 kcal. Merck notes kittens can be fed free choice instead.
• Older cats: AAHA says cats may actually need more calories later in life, not fewer. Our calculator keeps the adult factors for seniors and lets the scale decide.

How sure is that number?

Not very, and the sources say so. WSAVA’s 2011 guidelines say energy needs can vary by 50% in either direction for cats (30% for dogs); Merck uses 30% for both. For the house cat, a 50% spread runs from 141 to 422 kcal a day.

That is why every source calls the result a starting point. WSAVA’s owner FAQ suggests adjusting the amount every 2 weeks at first, based on your cat’s weight and body condition. If your cat gains on 281 kcal, the right number for that cat is lower; if it loses, higher.

Step 2: treats, then split the rest by calories

AAHA’s 2021 guidelines keep treats and extras to no more than 10% of the diet. For the house cat that is 28 kcal, which leaves 253 kcal for meals.

To mix wet and dry food, decide what share of those 253 kcal each food supplies, then convert each share with its own label. Here is the house cat on two example labels: a 3-oz (85-g) can with 90 kcal, and a dry food with 400 kcal per cup and 3,700 kcal per kg.

The same arithmetic works for any split. Divide the wet share’s kcal by the kcal per can, and the dry share’s kcal by the kcal per cup (or by kcal per kg, times 1,000, for grams). A kitchen scale in grams is more precise than a measuring cup; AAHA recommends weighing food for that reason.

Reading the label

The number you need is under the heading “Calorie Content.” AAFCO’s model regulation asks for it in kilocalories per kilogram and per familiar unit, such as a can or a cup. AAFCO says the requirement changed in 2014 and that more products show it as states adopt the model rule, so an older bag may lack it. If yours has no calorie statement, ask the manufacturer for the kcal per can or cup.

Check the can size as well as the kcal. A 3-oz can and a 5.5-oz can of the same food hold different amounts of energy, and the label’s figure is per can.

Wet food, dry food and water

Wet food carries a lot of water. Merck puts canned foods at 60% to more than 87% water and dry foods at 3–11%, and notes that dogs and cats eating mostly canned food generally drink less. Less drinking from the bowl on wet food is expected. Calories, not the food’s weight, decide how much your cat gets.

If you want your cat to take in more water, WSAVA’s FAQ suggests feeding at least some canned food and putting out more than one water station. Never limit water; Merck says healthy animals regulate their own intake. For a sense of how much cats drink and when thirst is a reason to call, see how much water a dog should drink, which has a section on cats.

Put it together, then let the scale decide

1. Weigh your cat, ideally on the same scale each time, and note the weight in kg (pounds × 0.4536).
2. Pick the factor that fits: neutered adult, intact adult, inactive, or kitten.
3. Work out the day’s calories, or let the calculator do it, and set aside up to 10% for treats.
4. Decide the split between wet and dry food by calories, and convert each share with its own label.
5. Weigh your cat again every 2 weeks. If it gains, trim the meals a little and recheck; if it loses without trying, tell your vet.

A cat that already carries extra weight needs a different plan. The calories come from the target weight, the loss has to be slow, and a cat should never be made to go without food. The cat weight-loss guide explains why.

This is general information, not veterinary advice — talk to your vet, or a veterinary nutritionist for a medical or weight-gain diet.

Next step

Enter your cat’s weight, life stage and the kcal from each label in the cat calorie and food calculator. It shows the daily range, the ±50% spread, and cans, cups and grams for up to two foods.