Both formats can be complete and balanced, so the honest answer is that this is not a safety question but an arithmetic one. Wet food is roughly 78% water and costs three to six times more per calorie; dry food is 6–10% water, cheaper, and leaves the cat to make up a deficit it is bad at making up. For most indoor cats the best answer is a mix, weighted toward wet if the budget allows and toward dry if it does not.
The water gap is the whole argument
A mouse is about 70% water. Kibble is 6–10%. A 4 kg cat needs roughly 200–240 ml of water a day, and a dry-fed cat typically takes in 60–100 ml from food and drinks 100–150 ml — often landing short. A cat on pâté at 78% moisture takes in 130 ml from two 85 g cans before drinking anything.
| Format | Moisture | Water from a 240 kcal day |
|---|---|---|
| Dry kibble, 4,000 kcal/kg | 8% | ~5 ml |
| Pâté, 75 kcal/100 g | 78% | ~250 ml |
| Gravy pouch, 70 kcal/100 g | 85% | ~290 ml |
Cats evolved as desert hunters with a weak thirst drive: they can concentrate urine past a specific gravity of 1.050 and still look fine, which is why underhydration shows up as disease rather than thirst.
Urinary and kidney risk: the strongest evidence
This is where the two formats are not equal. Higher water intake dilutes urine, lowers specific gravity, and reduces the supersaturation of struvite and calcium oxalate — the minerals behind most feline lower urinary tract disease. Cats with a history of blockage or crystals are put on wet food for that reason, and recurrence rates fall when urine is kept dilute, with a target specific gravity under 1.035.
For chronic kidney disease the stakes are higher: an IRIS 2–3 cat that eats wet food gets fluid without a subcutaneous drip. Renal diets come in both formats, but the canned one does the hydration work. If your cat refuses it, ask the vet about water added to kibble before home fluids.
Cost, calculated per 100 kcal
Work the price out per 100 kcal, not per bag.
- Mid-range dry: 2 kg at 4,000 kcal/kg = 8,000 kcal. At $18, that is $0.23 per 100 kcal, or about $0.55 a day for a 240 kcal cat.
- Supermarket pâté: 85 g cans at 75 kcal/100 g = 64 kcal per can. At $0.90 a can you need 3.75 cans, about $3.40 a day.
- Premium pâté: same calories at $2.20 a can, roughly $8.25 a day.
That gap is why most multi-cat homes cannot feed all-wet. But price and format are separate axes: $45 for 2 kg of premium kibble is $0.56 per 100 kcal against $1.41 for a supermarket can. Confusing the two is how people pay premium prices for 30% carbohydrate.
The dental claim does not survive scrutiny
Kibble shatters against the tooth and barely touches the gingival margin, where periodontal disease actually starts. Studies comparing dry-fed and wet-fed cats have not shown a meaningful difference in tartar or gingivitis once age and brushing are accounted for. The only products with a real claim carry a Veterinary Oral Health Council seal, and they work through a fibre matrix that scrubs, not through being dry.
What protects teeth is brushing with pet toothpaste several times a week, plus professional scaling when needed. Choosing kibble for dental reasons is choosing the wrong tool.
Body condition: the format changes how much you control
Dry food packs 350–430 kcal into 100 g, so a 15 g error in portion size is a 60 kcal error — a quarter of a cat's daily needs. Canned food at 75 kcal/100 g makes the same 15 g error worth 11 kcal.
Free-feeding works for one cat in stable condition and fails everywhere else: two cats, one bowl, and the confident one eats 40% more than it needs. If you do it, weigh the full 24-hour ration once and do not top up.
Where dry food genuinely wins
- Cost per calorie, by a factor of three to six.
- Staying fresh. An opened can grows bacteria within two hours; discard after 1–2 hours in the bowl, refrigerate the rest up to 48 hours.
- Travel. Kibble in a timed feeder covers a weekend; wet food does not. Some cats refuse pâté outright, and that does not yield to logic.
How to mix without overfeeding
Set the calorie total first, then assign a share to each format. A 4 kg indoor cat needing 240 kcal could take 144 kcal from pâté (about 190 g) plus 96 kcal from kibble (about 24 g). Weigh both. Do not add dry food on top of a full wet ration as a "snack" — that is the standard route to a 1 kg weight gain in a year.
| Split | Wet share | Dry share | Suits |
|---|---|---|---|
| Wet only | 100% | 0% | FLUTD history, CKD, diabetes, seniors |
| Mixed, wet-leaning | 60–70% | 30–40% | Most indoor adults with a moderate budget |
| Mixed, dry-leaning | 25–35% | 65–75% | Multi-cat homes, tight budgets |
| Dry only | 0% | 100% | Healthy young adult, fountain, measured portions |
Who should not be on dry food
Cats with a history of urethral obstruction, struvite or oxalate stones, or repeated cystitis belong on wet. Cats with CKD stage 2 and beyond belong on wet. Diabetic cats do best on high-protein, low-carbohydrate wet food, since carbohydrate under 10% dry matter reduces the insulin requirement in many cases. Seniors losing muscle need calorie-dense wet food: appetite falls before protein requirement does.
If your cat is currently dry-only and healthy, you do not have to change. Add a fountain, place three water bowls away from the food, and consider one wet meal a day. That single change often moves water intake more than switching brands ever will. Compare specific products in our food section, and check portion sizes with the calculator before changing anything.
Frequently asked
Can I feed wet and dry food in the same meal?
Yes, as long as the total calories for the day are fixed and both parts are weighed. Many cats digest mixed meals fine. Leave at least 30 minutes between a wet meal and dry food if your cat bolts food and vomits.
Does wet food cause dental disease?
No evidence supports that. Studies have not found meaningfully more tartar or gingivitis in wet-fed cats once age and brushing are controlled. Neither format cleans teeth; brushing does.
How long can wet food sit in the bowl?
One to two hours at room temperature. In hot weather, 30–45 minutes. Refrigerate leftovers in a covered container for no more than 48 hours, and never refreeze.