Pet Food Dry Matter Converter
Convert the guaranteed analysis on a dog or cat food label to a dry matter basis and compare two foods side by side, so wet and dry foods can be compared fairly.
Copy the as-fed percentages from each food's guaranteed analysis. Fill in one food to convert it, or both to compare them.
Enter the moisture and at least one nutrient for a food to see it on a dry matter basis.
Label figures are minimums (protein, fat) or maximums (fiber, moisture), not exact values, so treat small differences as noise. The carbohydrate estimate appears only when ash is entered for a food, and inherits the uncertainty of every other figure. Dry matter tells you how foods compare, not which one suits a particular animal: for animals with a medical condition, ask the vet.
Why labels need converting
The guaranteed analysis on a pet food label (called "analytical constituents" in Europe) gives each nutrient "as fed", which means water is included. A canned food can be three quarters water; a kibble is usually around a tenth. Put the two labels side by side and the canned food looks low in everything, simply because so much of it is water.
Converting to a dry matter basis takes the water out of the calculation, so you compare what is left: the food itself. It is the first step consultants take when a client asks whether one food has more protein or fat than another.
How the converter works
For each nutrient, the converter applies the standard formula:
Dry matter % = nutrient % ÷ (100 − moisture %) × 100
- Dry matter: 100 minus the moisture percentage. A food with 78 percent moisture has 22 percent dry matter.
- Each nutrient: its as-fed percentage divided by the dry matter, times 100.
- Carbohydrate (optional): most labels do not list carbohydrate. If you enter ash as well, the converter estimates it by difference: 100 minus moisture, protein, fat, fiber and ash. That estimate is then converted like the others.
Enter one food to convert it, or two to see them next to each other. The converter checks that the numbers make sense: moisture must be below 100 percent, and moisture plus nutrients cannot add up to more than 100.
A worked example
These are example figures, not real products.
| As fed | Canned food | Dry kibble |
|---|---|---|
| Moisture | 78% | 10% |
| Protein | 8% | 26% |
| Fat | 5% | 15% |
| Fiber | 1% | 4% |
| Ash | 2% | 7% |
On the label, the kibble seems to have more than three times the protein. On a dry matter basis:
- Canned food: 8 ÷ 22 × 100 = about 36.4 percent protein, with 22.7 percent fat and an estimated 27.3 percent carbohydrate.
- Dry kibble: 26 ÷ 90 × 100 = about 28.9 percent protein, with 16.7 percent fat and an estimated 42.2 percent carbohydrate.
Once the water is removed, the canned food is the higher-protein, higher-fat food of the two, and the kibble has more carbohydrate.
Limits to keep in mind
- Label figures are not exact. Protein and fat are usually minimums, fiber and moisture maximums. The real food can differ, so a difference of a point or two means little.
- The carbohydrate estimate carries every other figure's uncertainty. Use it to see which food is broadly higher, not as a measurement.
- Dry matter does not tell you calories per bowl. Two foods with the same protein on a dry matter basis can differ a lot in energy. To work out portions, use the calorie content on the label with the dog calorie calculator or the cat calorie calculator.
- It does not say which food is right. Life stage, the animal's health, digestibility, the ingredient list and how the animal does on the food over weeks all matter more than one number.
When not to rely on it
For an animal with kidney disease, a urinary condition, diabetes, food allergies or any other medical condition, nutrient levels are part of treatment. The vet or a veterinary nutritionist decides what the diet should contain, and a comparison like this is only a way to understand their advice. The same applies to puppies of large breeds and to pregnant or nursing animals.
Learn more
Our guide to how to read a pet food label explains the rest of the label: complete and complementary foods, the ingredient list and the claims to be careful with. To see where a consultant's advice stops and a vet's begins, read pet nutritionist vs veterinary nutritionist.
Frequently asked questions
What does dry matter basis mean on pet food?
It is the share of a nutrient once the water in the food is taken out of the calculation. Label figures include water, so a wet food looks low in protein beside a kibble even when, water aside, it contains more.
Where do I find the moisture of a pet food?
In the guaranteed analysis, called analytical constituents in Europe. If a label gives no moisture figure, check the manufacturer's information; without it, the food cannot be converted.
Is a higher protein figure on a dry matter basis always better?
No. It tells you how the foods compare, not which one suits a particular animal. Life stage, health, calorie content and the animal's response over time matter more, and animals with medical conditions need their vet's advice.