Dry-Matter Pet Food Comparisons: A Worked Example and Its Limits
PARTNER Editorial TeamDry-matter comparison removes water from the comparison basis. It can help you understand why a wet food's protein percentage looks lower than a dry food's percentage. It cannot, by itself, establish which food is better, more digestible or appropriate for your pet.
Start by asking whether both numbers are reported as fed—including the water in the food. If the basis is missing or unclear, ask the manufacturer before applying a conversion.
The calculation
For an as-fed nutrient percentage and a known moisture percentage:
Dry matter % = 100 − moisture %
Nutrient on a dry-matter basis = as-fed nutrient % ÷ dry matter % × 100
These formulas express the same nutrient relative to the food's nonwater portion. They do not measure the nutrient, test the food or create a feeding recommendation.
Two fictional labels
The following numbers are teaching examples, not PARTNER specifications or results from products we tested.
On smaller screens, swipe the table to see all columns.
| Example | Label figures used | Approximate calculation |
|---|---|---|
| Food A | 30% crude protein; 10% moisture | 30 ÷ 90 × 100 = 33.3% |
| Food B | 10% crude protein; 75% moisture | 10 ÷ 25 × 100 = 40% |
The initial 30-versus-10 comparison changes after accounting for water. But if those label values are a protein minimum and a moisture maximum, the results are only a rough comparison using limits. They are not the measured protein percentages of the foods, and they do not prove that Food B contains more protein than Food A in every batch.
AAFCO's guide to reading pet food labels explains the role of minimum and maximum nutrient guarantees. Keep those qualifiers attached to the numbers when recording a comparison.
Ask for the right additional information
A useful question to a manufacturer is: “Can you provide the typical nutrient analysis, its reporting basis and the calorie content for this exact recipe?” Keep the answer with the formula name, because information for another recipe is not interchangeable.
When your veterinarian needs a diet comparison for a health condition, ask which nutrients and basis they want. A dry-matter protein calculation does not answer questions about phosphorus, sodium, energy intake or the full nutrient profile. Do not estimate an unlisted mineral value from the ingredient list.
Keep three kinds of percentage separate
- Ingredient percentages describe recipe ingredients or categories.
- Nutrient guarantees provide specified minimums or maximums.
- Dry-matter values describe a reporting basis after excluding water.
An 8:1:1 recipe concept is not a protein calculation. Nor does an animal-origin ingredient percentage tell you the percentage of crude protein. Our existing raw-label explanation covers that distinction; this page focuses on the moisture calculation.
Make a comparison sheet you can actually use
Save the full label, exact recipe name, species and life stage beside each number. Mark whether the value is a guarantee or a typical analysis and whether it is as fed or dry matter. Leave unknown fields blank rather than filling them from another product.
Use the cat food label guide or dog food buying guide for the broader selection decision. The value of this calculation is a clearer question—not a winner chosen from one percentage.
Published by PARTNER Editorial Team for general education. Your veterinary team can advise on your pet's individual health and feeding needs.