How this calculator works
Dry matter is the part of a food that remains after its water is excluded. Dividing an as-fed nutrient fraction by the dry fraction puts foods with different moisture levels on a common mass basis. Listed nutrients must not overlap. Unlisted solids are a difference, not a measured carbohydrate analysis. Dry-matter comparison alone cannot establish digestibility, amino-acid adequacy or energy density.
Formula
Dry fraction = 1 - moisture fraction. Nutrient on dry matter = as-fed nutrient / dry fraction. As-fed nutrient = dry-matter nutrient × dry fraction. Moisture = 1 - as-fed/dry-matter nutrient.
Worked example
Food with 80% moisture and 8% protein contains 20% dry matter and 40% protein on that basis. Food with 10% moisture and 27% protein contains 30% protein on a dry-matter basis. Conversely, 40% dry-matter protein at 80% moisture is 8% as fed.
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Frequently asked questions
Why not compare the two protein percentages directly?
A wetter food includes more water in each gram. Removing water makes the nutrient mass fractions comparable.
Can moisture be 100%?
No dry matter would remain, so a nutrient percentage on a dry-matter basis would be undefined. This calculator requires some dry matter.
Are label guarantees exact?
Usually they are minima or maxima. Ask the manufacturer for typical analysis and energy data when making a detailed dietary comparison.