Why compare on a dry matter basis
Pet food labels list nutrients as fed, including water. Canned food is often about 75% to 80% water, while dry kibble is about 10%. A can that lists 10% protein may therefore contain more protein than a kibble listing 26%, once the water is removed. Converting to a dry matter basis puts both on the same footing.
Formula
Dry matter = 100% − moisture %
Nutrient on a dry matter basis = nutrient % as fed ÷ dry matter % × 100
Example
| Canned food | Dry kibble | |
|---|---|---|
| Moisture | 78% | 10% |
| Crude protein as fed | 10% | 26% |
| Protein on a dry matter basis | 45.5% | 28.9% |
| Crude fat as fed | 5% | 15% |
| Fat on a dry matter basis | 22.7% | 16.7% |
The canned food is far richer in protein once the water is removed.
Reading the guaranteed analysis
In the US, the guaranteed analysis lists a minimum for crude protein and crude fat and a maximum for crude fiber and moisture. The true values can be higher (for protein and fat) or lower (for fiber and moisture), so the dry matter result is an approximation.
Reference minimums (AAFCO, dry matter basis)
| Protein | Fat | |
|---|---|---|
| Adult dog | 18% | 5.5% |
| Puppy, growth and reproduction | 22.5% | 8.5% |
| Adult cat | 26% | 9% |
| Kitten, growth and reproduction | 30% | 9% |
These are minimums for a complete and balanced food, not ideal values. Cats are obligate carnivores and generally do well on higher protein.
Beyond percentages
- Compare foods on calories too: the energy content (kcal per kg or per cup) decides how much you feed.
- For a more precise comparison, some owners calculate grams of protein per 100 kcal.
- Look for an AAFCO statement saying the food is “complete and balanced” for your pet’s life stage.
- Ask your veterinarian before changing diets for pets with kidney, liver or digestive disease.