Dry matter basis calculator for dog food
Copy the guaranteed analysis from one or two dog food labels: moisture, protein, fat and fiber. You get each nutrient on a dry matter basis, so a canned food and a kibble can be compared side by side.
Tim de JongCopy the guaranteed analysis from each label. Start values: the Merck Veterinary Manual example.
Protein, dry matter basis
44.4%Canned food
Dry food has 27.3%. With the water taken out, Canned food has more protein, whatever the label numbers suggest.
| Dry matter basis | Dry food | Canned food |
|---|---|---|
| Dry matter | 88.0% | 18.0% |
| Crude protein | 27.3% | 44.4% |
| Crude fat | – | – |
| Crude fiber | – | – |
| kcal per kg DM | – | – |
Dry matter = 100 − moisture. Nutrient (DMB) = as-fed % ÷ dry matter % × 100. Guaranteed analyses are minimums and maximums, so results are close estimates, not exact contents.
Guaranteed analyses give minimums and maximums, not exact amounts, so dry matter figures are close estimates. Ask the manufacturer for a typical analysis if you need exact values.
What does dry matter basis mean?
The guaranteed analysis on a dog food label is given as fed: the percentages include the water in the food. That makes wet and dry foods impossible to compare directly, because a can is mostly water and a bag of kibble is not. Dry matter basis (DMB) removes the water from the sum and shows what share of the actual food solids is protein, fat or fiber. The Merck Veterinary Manual recommends comparing diets this way.
How do I calculate dry matter basis?
- Find the moisture on the label and subtract it from 100. That is the dry matter percentage.
- Divide the nutrient's label percentage by the dry matter percentage.
- Multiply by 100.
Nutrient (DMB) = nutrient as fed ÷ (100 − moisture) × 100
Worked example, from the Merck Veterinary Manual: a dry food with 24% protein and 12% moisture has 88% dry matter, so its protein on a dry matter basis is 24 ÷ 88 × 100 = 27.3%. A canned food with 8% protein and 82% moisture has only 18% dry matter, so its protein is 8 ÷ 18 × 100 = 44.4%. The can that looked three times lower in protein actually has more.
Dry matter protein by moisture: chart
The same label percentage means very different things at different moisture levels. Protein on a dry matter basis for a range of label values (the same maths works for fat, fiber or any other nutrient):
| Dry food | 8% water | 10% water | 12% water |
|---|---|---|---|
| 18% protein | 19.6% | 20% | 20.5% |
| 22% protein | 23.9% | 24.4% | 25% |
| 26% protein | 28.3% | 28.9% | 29.5% |
| 30% protein | 32.6% | 33.3% | 34.1% |
| Canned food | 72% water | 75% water | 78% water | 82% water |
|---|---|---|---|---|
| 6% protein | 21.4% | 24% | 27.3% | 33.3% |
| 8% protein | 28.6% | 32% | 36.4% | 44.4% |
| 10% protein | 35.7% | 40% | 45.5% | 55.6% |
| 12% protein | 42.9% | 48% | 54.5% | 66.7% |
A canned food listing 8% protein can carry more protein in its solids than a kibble listing 26%: moisture changes the picture that much.
How much water is in wet and dry dog food?
| Food type | Water | Dry matter |
|---|---|---|
| Dry kibble | about 10% | about 90% |
| Semi-moist | 25 to 40% | 60 to 75% |
| Canned | 68 to 78% | 22 to 32% |
Water is also why wet food portions are so much bigger for the same calories. If you feed both, the wet and dry food calculator splits the calories between them.
How to compare two dog foods on a dry matter basis
Enter both labels in the calculator and read across the dry matter rows. A few tips make the comparison more useful:
- Convert every food, even two kibbles. Take a made-up kibble with 14% fat and 10% moisture and a can with 5% fat and 78% moisture: on the label the kibble looks almost three times fattier, but on a dry matter basis it is 15.6% against 22.7% for the can.
- Compare foods for the same life stage. The nutritional adequacy statement says whether a food is complete for growth, maintenance or all life stages; a puppy food and an adult food are built to different targets.
Why dry matter results are estimates
AAFCO requires the guaranteed analysis to list the minimum crude protein and fat and the maximum crude fiber and moisture. The real contents can be higher than a minimum or lower than a maximum, so a dry matter figure worked out from the label is a close estimate rather than the exact amount. "Crude" refers to the lab method used, not the quality of the nutrient.
For exact numbers, ask the manufacturer. WSAVA's guidelines say pet food companies should be able to provide an average or typical analysis for all essential nutrients in their foods, and suggest being cautious about a brand that can't. Dry matter basis also says nothing about calories per bowl; to work out how much to feed, use the dog feeding calculator with the calorie statement on the label.
Frequently asked questions
Why does canned dog food look so low in protein?
Because most of the can is water. In the Merck Veterinary Manual example, a canned food with 8% protein and 82% moisture actually has 44.4% protein once the water is removed, more than a dry food with 24% protein on its label (27.3% on a dry matter basis).
Where do I find the moisture on a dog food label?
In the guaranteed analysis. AAFCO rules require every label to state the minimum crude protein and crude fat and the maximum crude fiber and moisture, so the moisture figure you need is always there.
Do I need dry matter basis to compare two dry kibbles?
It matters less, because most dry foods have similar moisture, but it still makes the comparison exact. If one kibble lists 10% moisture and another 12%, converting both takes that difference out.
Is dry matter basis the same as the label percentage?
No. Label percentages are 'as fed', meaning they include the water in the food. Dry matter basis is what the same nutrient would be if all the water were removed, so it is always higher than the label figure for a food that contains water.
Sources
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