Compare Two Pet Food Labels Fairly: The Dry-Matter-Basis Calculator

By Morgan Reyes

The Short Answer

Divide the as-fed percentage by (100 minus the moisture percentage) over 100, and you get the dry-matter-basis number. That single conversion is what makes a wet food's guaranteed analysis and a dry food's guaranteed analysis actually comparable, and it's also the basis AAFCO itself uses to set nutrient minimums.

The formula: DMB% = As-Fed% ÷ ((100 − Moisture%) ÷ 100)

One worked example before the calculator: a dry kibble listing 26% protein at 10% moisture works out to 26 ÷ 0.90 = 28.9% protein on a dry-matter basis. AAFCO's own guidance on substantiating nutritional adequacy states the reasoning plainly: an as-fed value and a dry-matter value differ "proportional to the moisture (water) content of the food," which "makes direct comparison... impossible without first correcting one or the other set of values."

The Calculator

Enter a value from any label's guaranteed analysis and its moisture percentage, and the calculator converts it for you, both directions.

The second mode (Profile minimum → as-fed equivalent) runs the same formula the other way. It's useful for a different question: instead of asking "what's this food's real dry-matter number," it asks "given this food's moisture content, what as-fed number on the label would actually clear an AAFCO Profile minimum." AAFCO's own document works this exact example: a 22.5% Profile minimum, corrected for a food at 90% dry matter (10% moisture), becomes 22.5 × 0.90 = 20.25% as-fed. A label reading 22.5% as-fed at that moisture level is already clearing the minimum with room to spare, not sitting right at the edge of it.

Two Worked Examples

The formula is the same both times. What it reveals is different.

Wet vs. dry, the comparison that starts most of this confusion. A dry kibble listing 26% protein looks like it beats a canned food listing 10% protein by a wide margin. It doesn't. Once both are corrected for moisture, the canned food's 10% protein at 78% moisture works out to 10 ÷ 0.22 = 45.5% on a dry-matter basis, well above the kibble's 28.9%. The ranking doesn't just narrow, it flips. This is the exact pair of numbers used on this site's own label-reading guide, so the two pages agree to the decimal.

A catch that moisture correction alone doesn't catch. AAFCO's document works a second, less obvious example: a canned cat food listing 9% protein at 75% moisture converts to 9 ÷ 0.25 = 36% on a dry-matter basis, comfortably clearing a typical adult-cat minimum. On the moisture correction alone, this food looks fine. But AAFCO's actual nutrient profiles are pegged to a standardized 4000 kcal ME/kg of dry matter, and a food with a lower actual caloric density delivers less of every nutrient per calorie an animal actually eats, since animals eat to meet their energy needs, not to hit a percentage. Correcting the same food's calcium and phosphorus for its real caloric density (rather than moisture alone) drops calcium from a dry-matter-basis 0.89% to below the 1.0% minimum, and phosphorus from 0.71% to below the 0.8% minimum. A food that passes on moisture correction can still fail once caloric density is accounted for too.

Why This Isn't Just a Convenience

AAFCO's own nutrient minimums are stated on a dry-matter basis, which is the actual reason this conversion matters, not just a trick for comparing two bags. A regulator can't set a meaningful nutrient floor in as-fed terms, because as-fed values shift with a food's water content and tell you nothing about the food's actual composition. Dry-matter basis strips that variable out, which is why it's the basis AAFCO itself checks a food's adequacy against.

That has a direct, practical consequence for a reader holding two bags: an as-fed comparison between a wet food and a dry food isn't a wrong comparison, it's an answer to a different question. It tells you how much water is in each bag, which matters for a different reason (hydration, palatability, cost per calorie), but not whether one food is nutritionally denser than the other. The energy-density example above goes a step further: even a correct dry-matter conversion can still overstate a food's real adequacy if its caloric density is unusually low, which is exactly the kind of thing a calculator makes checkable in a way a bare formula written out on a page doesn't.

Bottom line: divide an as-fed percentage by the dry-matter proportion (100 minus moisture, over 100) to get a number you can actually compare across foods and against AAFCO's own minimums. A 26%-protein kibble at 10% moisture is 28.9% on a dry-matter basis; a 10%-protein canned food at 78% moisture is 45.5%, which beats the kibble despite looking far lower on the label. And a food that clears its dry-matter minimum can still come up short once caloric density is corrected for too, which is worth checking on any food marketed as unusually protein-dense.

FAQ

Why can't I just compare the protein percentages printed on two bags?

Because the guaranteed analysis is as-fed, and wet and dry foods carry very different amounts of water. See the formula and worked examples above.

What is dry-matter basis, and why does AAFCO use it?

A food's nutrient content with the water mathematically removed. AAFCO's own Profile minimums are set on this basis, which is why it's the number that actually matters for checking adequacy, not just for comparing two labels to each other.

Does a higher dry-matter-basis number mean a better food?

Not by itself. See the energy-density example above for a case where a food clears its dry-matter minimum but still comes up short once caloric density is corrected for too.

Keep Reading

• Read Any Pet Food Label in 60 Seconds. The four-step label scan this calculator's first worked example comes from.
• The Cat Nutrition Essentials Checklist. Where this site's own taurine minimums are already stated on a dry-matter basis.

A Note on Scope

This page covers a single arithmetic conversion (moisture correction between as-fed and dry-matter basis) and is not a recommendation for or against any specific food or brand. It doesn't evaluate ingredient quality, sourcing, or overall nutritional adequacy beyond the specific numbers you enter.

Sources

• AAFCO, Methods for Substantiating Nutritional Adequacy of Dog and Cat Foods, section "Correcting for Moisture Content." Fetched and extracted directly 30 July 2026. Source for the formula, the 26%/10%/28.9% and 10%/78%/45.5% examples, the 22.5%/90%/20.25% inverse example, and the 9%/75%/36% energy-density example.