How the calculation works
A guaranteed analysis is printed as fed, which means water is still part of the number. Removing the moisture leaves the dry matter, and every nutrient is then expressed as a share of it.
DMB % = nutrient % ÷ (100 − moisture %) × 100
A wet food with 10% protein and 78% moisture has 22% dry matter, so 10 ÷ 22 × 100 = 45.5% protein DMB.
Why wet and dry food cannot be compared directly
Wet food is mostly water, so its label numbers always look low. Once both foods are converted to dry matter the ranking often flips.
- Wet food: 10% protein, 78% moisture → 45.5% protein DMB.
- Dry food: 30% protein, 10% moisture → 33.3% protein DMB.
The wet food is the higher-protein food, even though its label shows a smaller number.
Where to find the values
- Protein and moisture are part of the guaranteed analysis on the packaging.
- Phosphorus is rarely printed. Ask the manufacturer for the typical analysis, which normally lists it.
- Guaranteed analysis values are minimums and maximums, not exact amounts. A typical analysis is more precise.
What the reference points mean
Around 0.8% phosphorus DMB is the figure most often cited for feline renal-support diets, and 40% protein DMB is a common dividing line between moderate and high protein foods. Both are discussion points with your veterinarian, not verdicts on a food.
This tool does not give dietary advice
The calculator converts label numbers. It does not recommend a food, build a diet plan, or replace your veterinarian, who knows your cat's diagnosis, bloodwork and appetite.
FAQ
What does DMB mean on a cat food label?
DMB stands for dry matter basis — the nutrient value after water is removed from the calculation. It puts wet and dry foods on the same scale.
Why can't I compare wet and dry cat food directly?
Label values are printed as fed and wet food is mostly water, so its numbers look small. After conversion, a wet food with 10% protein can hold more protein per gram of food than a dry food with 30%.
What phosphorus level is used for renal-support foods?
Roughly 0.8% on a dry matter basis is the value most often cited for feline renal diets. It is a reference point for a conversation with your vet, not a rule that fits every cat.
The label does not list phosphorus. What now?
Contact the manufacturer and ask for the typical analysis. It usually includes phosphorus, and that is the number to enter here.
Is my data sent anywhere?
No. The calculation runs entirely in your browser. Nothing is uploaded, saved or shared.