A tin of wet cat food says 10% protein. A bag of kibble says 35% protein. Strip out the water and the picture changes: wet food is roughly 80% water, kibble roughly 10%, and once you account for that, the wet food often delivers more protein per gram of solid nutrition.
Dry Matter Basis (DMB) is the calculation that makes this comparison fair. The formula is simple: divide the nutrient percentage by (100 minus the moisture percentage), then multiply by 100.
Work out a product's dry matter basis
Pick any product to see its protein and fat once the water is stripped out. When a label does not state moisture, test a moisture range yourself to see where the figure would land.
Choose a brand and product to see the breakdown.
How to read these figures
A guaranteed analysis is a set of guarantees, not an exact recipe. Protein and fat are minimums, moisture and fibre are maximums. So any dry matter basis from a label is an approximation: sharpest when moisture is stated, looser when it is assumed. Still useful for comparing foods, just not laboratory exact.
Manual Calculator
Enter the values from any label to calculate DMB. Use a range when you are estimating a moisture you cannot see stated.
Real Examples
Here are real products from our database, sorted by DMB protein. Notice how the percentage changes completely once you account for moisture.
| Product | Format | Label | Moisture | DMB Protein |
|---|---|---|---|---|
| Tiki Cat After Dark Chicken in Broth | Canned | 12% | 83% | 70.6% |
| Fancy Feast Grilled Chicken Feast in Gravy | Canned | 11% | 80% | 55% |
| Feline Natural Freeze-Dried Chicken Feast | Freeze-Dried | 48% | 8% | 52.2% |
| Taste of the Wild Rocky Mountain | Kibble | 42% | 10% | 46.7% |
| Ziwi Peak Air-Dried Beef | Air-Dried | 38% | 14% | 44.2% |
| Black Hawk Original Adult Chicken | Kibble | 32% | 10% | 35.6% |
Tiki Cat lists 12% protein on the tin but delivers 70.6% on a dry matter basis. That is nearly double the protein density of Black Hawk Original Adult Chicken, a kibble that lists 32% on the packet yet works out at 35.6% once the water is stripped out.
The Same Applies to Fat
Fat follows the same pattern. A wet food listing 6% fat with 78% moisture is actually 27.3% fat on a dry matter basis. The same conversion matters if you are managing your cat's weight or comparing calorie density between products.
Carbohydrate, the Number the Label Leaves Out
Cat food labels never state carbohydrate. The guaranteed analysis lists protein, fat, fibre, moisture, and sometimes ash, but the carbohydrate, which veterinary chemists call nitrogen-free extract, is left to be worked out by difference. That matters for an obligate carnivore: cats use animal protein and fat efficiently and have only a limited need for carbohydrate [4], so the carbohydrate fraction is one of the more telling things about a recipe, and it is the one figure the label leaves blank.
To estimate it, subtract everything the label does state from 100: carbohydrate is roughly 100 minus protein, minus fat, minus fibre, minus moisture, minus ash. The catch is ash. Most Australian labels do not print it, and many leave out fibre as well, so unless both are stated the result is an estimate rather than a measured figure. A reasonable working assumption is around 6 to 8% ash for a typical complete cat food. With that, a kibble at 32% protein, 14% fat, 3% fibre, 10% moisture, and 7% ash works out to about 34% carbohydrate as fed, or roughly 38% on a dry matter basis once you strip the 10% moisture out.
When moisture is not stated
Not every brand publishes moisture. Several leave it off the guaranteed analysis altogether, at least on their websites, which means there is no measured figure to divide by.
When that happens we do not assume a number or present a fixed dry matter basis as though it were fact. Instead, the calculator above lets you test a moisture range and shows the band the result would fall into, clearly flagged as an estimate. If you have the packet in front of you, the manual calculator works from whatever the label does state.
A guaranteed analysis is a set of guarantees rather than an exact recipe. Protein and fat are minimums and moisture is a maximum, so even a dry matter basis worked out from a stated moisture is a close approximation rather than a laboratory figure. The numbers are still the fairest way to line up wet against dry, they are just not precise to the decimal.
What DMB Does Not Tell You
DMB is a useful comparison tool, but it has limits.
It tells you nothing about ingredient quality. A food with 40% DMB protein could be sourcing that protein from whole chicken breast or from rendered feathers and plant isolates. The protein percentage is the same either way. You still need to read the ingredient list to understand where the nutrients are coming from.
It does not account for digestibility. Some protein sources are more bioavailable to cats than others. Plant proteins like pea protein, soybean meal, and corn protein meal contribute to the total protein number on the label but are less biologically useful to cats than animal proteins [4]. Cats are genetically adapted to derive energy from animal fat and protein [3], and when given free choice they consistently target a diet of approximately 52% protein by energy [1][2].
It does not reflect calorie density. A freeze-dried food with 50% DMB protein at 5,000 kcal/kg is a very different feeding proposition to a wet food with 50% DMB protein at 1,000 kcal/kg. You would feed far less of the freeze-dried product by weight to meet your cat's daily energy needs.
How to Use This Information
When comparing cat foods: check the moisture content, work out DMB protein and fat with the calculator above, compare those figures rather than the label numbers across the products you are weighing up, read the ingredient list to understand where those nutrients are coming from, and factor in calorie density if you are portion-conscious.
In practice
The numbers on a cat food label are not wrong, but they are incomplete. A 10% protein wet food and a 35% protein kibble are not as different as they appear. In many cases, the wet food delivers more protein per gram of actual food.
Nutritional data sourced from manufacturer websites and verified against Australian retail listings, April 2026.
Related reading
- Why Your Cat Cannot Just Eat Anything. The peer-reviewed research on feline macronutrient selection that explains why the DMB numbers matter.
- The Label Guide. How to read the ingredient list that sits behind the guaranteed analysis numbers.
- Portions. Work out how many grams of a given food your cat needs per day.
Sources
[1] Hewson-Hughes, A.K. et al. (2011). Geometric analysis of macronutrient selection in the adult domestic cat, Felis catus. Journal of Experimental Biology, 214(6): 1039-1051.
[2] Hewson-Hughes, A.K. et al. (2013). Consistent proportional macronutrient intake selected by adult domestic cats despite variations in macronutrient and moisture content of foods offered. Journal of Comparative Physiology B, 183: 525-536.
[3] Montague, M.J. et al. (2014). Comparative analysis of the domestic cat genome reveals genetic signatures underlying feline biology and domestication. Proceedings of the National Academy of Sciences, 111(48): 17230-17235.
[4] Zoran, D.L. (2002). The carnivore connection to nutrition in cats. Journal of the American Veterinary Medical Association, 221(11): 1559-1567.
[1][2] were conducted at the WALTHAM Centre for Pet Nutrition (Mars Petcare) with independent academic collaborators from the University of Sydney and Massey University. Conflict of interest noted per KibbleGuide editorial standards. [3][4]: no industry affiliations identified.
Without limiting our Terms, ingredients and product information listed here require independent verification. Information on this page is sourced from publicly available sources and while we take reasonable care to verify accuracy, we do not warrant that it is complete, current, or error-free. Nothing on kibbleguide.com.au constitutes veterinary or nutritional advice. Consult a qualified veterinarian for guidance specific to your pet. See our Terms of Use for full details.