Both can be a complete diet for a cat, but wet food carries about 4 times fewer calories per gram because of its high water content, which is why the portions look so much bigger. The choice is not really about which type is healthier in the abstract. It comes down to what a specific cat needs most: water, cost, or convenience.
Calories: why the portion sizes look so different
A typical dry food runs 350 to 420 kcal per 100 grams, while a typical wet food runs 70 to 110 kcal per 100 grams. A spayed, indoor 9 lb cat needs roughly 240 kcal a day: that is about 0.6 cups of a 400 kcal/cup dry food, but the equivalent in wet food looks like a much bigger bowl for the same energy.
The exact portion depends on the calorie count on the specific label, not on the food type in general: two different wet cans can differ by 30% in calories. Enter the number from your label into the cat food calculator for an exact amount rather than eyeballing a bowl.
Water: the strongest practical argument for wet food
Domestic cats descend from a desert-adapted ancestor and physiologically do not feel strong thirst even when intake is low. The signal that tells a dog or a human to drink is weak in cats. The result: a cat on dry food alone can easily take in less water than it needs, which raises the risk of concentrated urine, urinary crystals, and chronic kidney disease later in life.
Wet food is about 75 to 80% water, so a cat eating mostly wet food gets a large share of its daily fluid straight from meals, without ever drinking much from the bowl. This is the main clinical reason vets recommend at least partial wet feeding, especially for cats with a history of urinary issues.
The dental myth
A common claim is that dry food "scrapes off" tartar through chewing. In practice most cats crunch a kibble with one quick bite rather than grinding it against the tooth surface, and studies show a negligible effect on tartar from ordinary dry food. The exception is dental-specific formulas with a particular kibble shape and texture designed for that purpose, which is a different product from standard dry food.
Cost per day
Dry food almost always costs less per calorie because it carries far less water weight to package and ship for the same energy content. The gap in US prices typically runs 30 to 60% in favor of dry food per calorie, though premium wet cans and budget dry foods can narrow that difference in specific cases.
Mixed feeding: the most common practical choice
Many vets recommend a combination: dry food stays available through the day for convenience and cost, while one or two wet meals add water and variety. The calculator handles a split easily. Divide the daily calories between the two types by a chosen ratio, say 70% dry and 30% wet, and enter the calorie count for each separately.
| Dry food | Wet food | |
|---|---|---|
| Calories per 100 g | 350 to 420 | 70 to 110 |
| Water content | about 10% | 75 to 80% |
| Cost per calorie | lower | higher |
| Storage after opening | weeks | up to 24 hours refrigerated |
Frequently asked questions
Can a cat live on wet food alone?
Yes, as long as it is labeled complete and balanced, not a treat or topper. Many cats with urinary issues are switched to fully wet diets on a vet's recommendation.
Does wet food damage teeth more than dry?
There is no evidence for that. Tartar buildup mostly comes down to individual predisposition and hygiene, not food type, aside from dental-specific formulas.
Why does wet food cost more for the same calories?
Because 75 to 80% of the can's weight is water, which gets packaged, shipped and priced as food rather than as water.
How do I work out the right portion for mixed feeding?
Use the cat food calculator: enter your cat's weight for the daily calorie target, then split that number between the two food types using the calorie count on each label.
For a cat with diagnosed kidney, urinary or diabetic disease, the choice between wet and dry food should be made with the treating veterinarian, not on general guidance alone.