Guaranteed analysis informs about the amount of a given type of ingredient is present by weight (in %) but it also includes moisture. Dog foods vary very much in the quantity of moisture they contain.


Converting the % given in guaranteed analysis to a dry matter basis eliminates moisture variability.

We convert guaranteed analysis given in the dog food label into a dry matter basis doing the following steps:

Example: Guaranteed analysis

Nutrients Percentage
Crude Protein 29 %
Crude Fat 16 %
Crude Fiber 9.6 %
Moisture 7.8 %

Carbohydrate Content

Carbohydrate content has really been intentionally absent from dog food nutrition labels. However, the volume of all dog foods consists of four major nutrients:

  • Proteins
  • Fats
  • Carbohydrates
  • Moisture

Additionally, dog food products include ash.  Ash content usually measures about 5 – 8 % of ended product.  Thus we normally use about 8 percent as a standard for this element.


Ash is the non-combustible mineral residue which is left over after burning away all the protein, fats and carbohydrates.

Protein, fat, ash, carbohydrate and water content must account for approximately 100 percent of the total pre-cooking weight of dog foods. We don’t use crude fiber, because fiber is a carbohydrate to.

So, we add up the given percentages of protein, fat and moisture from guaranteed analysis plus the ash % (we use an 8 % value). Then we subtract the obtain number from 100.

The remaining percentage is a rough estimate of the carbohydrate portion of the food.


  • Crude protein: 29 % + crude fat: 16 % + moisture: 7.8 % + ash: 8 % = 39.2%
  • Estimated carbohydrate content: 100 % – 60.8% = 39.2%

Dry Matter %

We subtract the moisture content from the guaranteed analysis from 100.  Thus, we obtain the percentage of dry matter in the food overall.


  • 100 % – Moisture: 7.8% = 92.2 %

Protein, Fat, fiber and carbohydrates in a dry matter basis

The convert protein, fat, fiber and carbohydrates percentages calculated before to dry matter basis we divide the percentage of each nutrient by the overall percentage of dry matter, and then multiply by 100.


  • Protein on a dry matter basis: (Crude protein: 29% / Dry matter: 92.2 %) x 100 = 31 %
  • Fat on a dry matter basis: (Crude fat: 16% / Dry matter: 92.2 %) x 100 = 17 %
  • Fiber on a dry matter basis: (Crude fiber: 9.6% / Dry matter: 92.2 %) x 100 = 10 %
  • Protein on a dry matter basis: (Estimated carbohydrates: 39.2% / Dry matter: 92.2 %) x 100 = 43 %


Nutrient analysis on a dry matter basis

Nutrients Percentages
Protein 31 %
Fat 17 %
Fiber 10 %
Carbohydrates 43 %


Guaranteed analysis, also called the “as fed” basis, is not useful in comparing foods. If you use the information given in the guaranteed analysis to compare foods, it is essential to do it on a dry matter basis.