As-fed versus dry matter

As-fed and dry matter are the two bases on which a nutrient level can be expressed, and confusing them is one of the most common errors when comparing foods. An as-fed figure is the percentage in the product exactly as it comes out of the bag or tin, water included, whereas a dry matter figure removes the water first, so it describes the food's true nutrient concentration once moisture is stripped out (FEDIAF, 2024). This distinction is decisive when comparing kibble with wet food, because the two differ enormously in [moisture](/glossary/moisture): dry food typically sits under 10 percent water while wet food often exceeds 75 percent. The consequence is striking. A wet food declaring 10 percent protein as-fed can actually be richer in protein than a kibble declaring 25 percent, once both are recalculated on a dry matter basis, simply because so much of the wet food's weight is water. The conversion is straightforward: divide the as-fed nutrient by the food's dry matter fraction (100 minus the moisture percentage). Without doing this, the [guaranteed analysis](/glossary/guaranteed-analysis) or [analytical constituents](/glossary/analytical-constituents) numbers printed on packs are not directly comparable across formats, which is exactly the trap that makes wet food look weaker than it is. It also underpins any honest [NFE carbohydrate estimate](/glossary/carbohydrate-estimate-nfe). For more on putting label figures on equal footing, see the [Petipedia glossary](/glossary).

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