How Much Wet Food, Dry Food and Water Does a Cat Need Each Day?

Most feeding questions start with a ratio: half wet and half dry, or a can in the morning and a scoop at night. The veterinary references we rely on do not set a fixed wet to dry ratio for adult cats. They give a way to estimate how many calories a cat needs and a limit on treats, and they say fresh water should always be out. Once the calorie number is in place, the wet and dry split becomes a choice you can make for your own cat and your own routine.

Step 1: Estimate Daily Calories

Veterinarians usually start from the resting energy requirement (RER), the energy a cat uses at rest. The Merck Veterinary Manual gives it as RER = 70 × (body weight in kg)^0.75, where ^0.75 means "to the power of 0.75" (any phone calculator can do it). The formula works in kilograms, so divide your cat's weight in pounds by 2.2 first.

To get the daily maintenance figure, multiply RER by a factor for the cat's life stage. Merck lists 1.4 for intact adult cats, 1.2 for neutered adults, 1.0 for adults prone to weight gain and 2.5 for kittens. When a maker's feeding chart is missing, Pettings estimates the daily amount the same way, with 1.2 (1.0 for weight control foods).

For an adult prone to weight gain (factor 1.0), use the RER column. For kittens, our Kitten Feeding Chart shows the amounts printed on real bags.

These are first guesses. Merck notes that a cat may need as much as 30% more or fewer calories than another cat of the same weight. If your cat is not at its ideal weight, ask your veterinarian which weight to use.

Step 2: Set Aside the Treat Budget

The World Small Animal Veterinary Association (WSAVA) says treats should make up less than 10% of a cat's daily calories. Its table puts that limit at about 24 kcal a day for a cat of 4.5 kg (about 10 lb).

So plan meals for 90% of the calorie target, or the full target if your cat gets no treats. Treat 10% as an upper limit: a 2025 study in Veterinary Sciences found that cutting complete food to make room for treats may reduce the intake of essential nutrients, especially for neutered or indoor cats that already eat less than the label suggests.

Step 3: Split Calories Between Wet and Dry

Decide what share of meal calories comes from wet food and what share from dry. Then split by calories, not by weight, since wet and dry foods differ so much in energy:

amount per day = calories you give that food ÷ calories per unit on the label

US labels list kcal/kg plus kcal per can (wet) or per cup (dry). Divide by kcal per can for cans a day or by kcal per cup for cups a day. For ounces, divide kcal/kg by 35.3 to get kcal per ounce.

A worked example: a neutered cat weighing 10 lb (4.5 kg) needs about 261 kcal a day. Keeping 10% for treats leaves 235 kcal for meals. Assume a wet food at 28 kcal per ounce with 78% moisture and a dry food at 108 kcal per ounce with 10% moisture. These are example label values, not real products; swap in the numbers from your own foods.

Calories stay the same in every row; only the amount of food and the water it brings change.

The dry foods on Pettings hold between 254 and 633 kcal per cup, so the same calories can mean noticeably different cups. These are the dry foods with the highest Ingredient score among those with nothing on the Avoid List and a Nutrition score of at least 6, one per brand:

Is There an Ideal Wet to Dry Ratio?

Splits like 80/20 or 70/30 circulate online, but we did not find a recommended ratio in any of the veterinary references Pettings uses. Cornell Feline Health Center says the key requirement is that a food is complete and balanced, and that wet food can be fed in addition to dry or instead of it.

The ratio mainly changes how much water comes from food. In the example above, a 10 lb cat gets about 0.2 fl oz of water a day from an all dry diet and about 6.2 fl oz from an all wet one. Otherwise, pick the split your cat accepts and you can keep up. If your veterinarian wants your cat taking in more water, ask what share of wet food to aim for.

Step 4: Plan for Water

Merck puts the water need of most mammals in a comfortable environment at about 44 to 66 ml per kg of body weight a day, roughly 0.7 to 1 fl oz per pound. It adds that the amount depends on diet, environment, activity and health. For a 10 lb cat that range is roughly 6.7 to 10 fl oz (200 to 300 ml) a day, counting both drinking water and the moisture in food.

Merck gives canned foods a moisture range of 60% to over 87% and dry foods 3% to 11%, and notes that cats eating mostly canned food generally drink less.

In a study of six healthy adult cats fed the same food at four moisture levels, cats drank more water as the food got drier but still took in less water overall: about 4.9 fl oz (145 ml) a day on the 73% moisture diet against about 3.5 fl oz (103 ml) on the 6% moisture diet. The sample was small, so read it as a sign of how cats respond rather than a target.

Whatever the ratio, Merck and Cornell both say fresh water should always be available, and Cornell adds that this is especially important for cats that eat only dry food. Merck also notes that offering more than one water source encourages drinking.

Step 5: Decide How Many Meals

Cornell's guidance by age:

Cornell also says that leaving dry food out all day works for some cats but leads others to overeat, and that food left out for grazing should be replaced with new food every day. Feeding wet at one meal and measured dry at the other keeps each daily total easy to track.

Step 6: Check and Adjust

Feeding instructions on labels are based on the needs of the average cat, so a less active cat may get more than it needs if you follow the bag exactly. Weigh your cat every few weeks, ask your veterinarian how to assess body condition, and adjust the calorie target in small steps.

If your cat has a medical condition, is pregnant or nursing, or is on a prescribed diet, the numbers above do not apply. Ask your veterinarian for a plan.

Quick Reference

• Convert weight to kilograms (pounds ÷ 2.2) and calculate RER: 70 × (weight in kg)^0.75.
• Multiply by the life stage factor (1.2 for most neutered adults).
• Keep up to 10% for treats.
• Choose a wet and dry split by calories.
• Convert calories to cans, cups or ounces using each label's calorie figures.
• Keep fresh water out at all times, ideally in more than one spot.
• Recheck weight and body condition and adjust.

Every food page on Pettings shows the calories from the label. You can browse all dry foods or read How to Read a Cat Food Label.

Sources

• Merck Veterinary Manual, "Nutritional Requirements of Small Animals": RER, life stage factors, water needs, food moisture.
• WSAVA, "Feeding Treats to Your Cat" (2025): the 10% limit and calories by body weight.
• Cornell Feline Health Center, "How Often Should You Feed Your Cat?" (edited 2024): meals by age, free feeding, water.
• Buckley CMF, Hawthorne A, Colyer A, Stevenson AE, "Effect of dietary water intake on urinary output, specific gravity and relative supersaturation for calcium oxalate and struvite in the cat", British Journal of Nutrition, 2011: water intake at four moisture levels.
• Príncipe LA and others, "Assessment of the Nutritional Impact of the 10% Snack Recommendation in Pet Diets", Veterinary Sciences, 2025.
• Food figures from the Pettings food pages; calories copied from the makers' labels.

These figures are starting points, not medical advice.