If you are comparing pet foods, one place to look is the Guaranteed Analysis on the label. There are other important comparisons (like ingredients) but the Guaranteed Analysis will always contain essential nutritional values like protein, fat, fiber, and moisture.
At minimum, many state regulations require a pet food to guarantee the minimum percentages of crude protein and crude fat, and the maximum percentages of crude fiber and moisture. The "crude" term refers to the specific method of testing the product, not to the quality of the nutrient itself.
Some manufacturers include guarantees for other nutrients as well. This calculator allows you to compare protein, fat, fiber, ash, and phosphorus.
Guarantees are declared on an "as fed" or "as is" basis, that is, the amounts present in the product as it is found in the can, bag, or other packaging. This doesn't have much bearing when the guarantees of two products of similar moisture content are compared. However, when comparing the guaranteed analyses between dry and canned or frozen products, one will note that the levels of crude protein and most other nutrients are much lower for the canned, moist or frozen product. This can be explained by looking at the relative moisture contents. Canned, moist or frozen foods typically contain 75-95% moisture, whereas dry foods typically contain only 5-14% moisture. To make meaningful comparisons of nutrient levels between a canned and dry, frozen and dry, or even two dry products with different moisture levels, they should be expressed on the same moisture basis.
The most accurate means of comparing analysis is to convert the guarantees for both products to a moisture-free or dry matter basis (zero percent moisture). Without making this conversion, youre essentially comparing apples to oranges and thereby drawing incorrect conclusions.
What is Dry Matter Basis?
Dry matter basis is a representation of nutrients which ignores the moisture content of the food. In other words, its the amount of protein, fat, and fiber which would be reported if the products moisture were completely removed. By converting the as fed basis percentages to dry matter basis, we can make meaningful comparisons between products of various moisture contents.
Pet food products with high moisture often report protein percentages below 10%. Its almost impossible to find dry products with protein percentages below 15%. Does this mean that manufactures are including less protein in wet foods? Absolutely not, the difference lies in the moisture.
If one were to cook wet dog, cat, or fish food, the moisture percentage would decrease and the protein percentage would increase. In essence, comparing the nutrients of two products with different moisture percentages is very misleading.
This calculator was created to make it easier to compare nutrient values. Simply input the values from the two products you are comparing to convert both to a dry matter basis.
Use the slider to get close to the value you are inputting and then use the plus or minus button for precise adjustments to enter the exact value. Enter the values of the first product on the first screen and then tap the next button. Enter the values for the second product on the second screen and then tap the next button. The dry matter values of both products will appear side by side on the third screen for you to compare.