How to Determine the Percentage of Fat by Weight in Food

The United States Food and Drug Administration requires commercial foods to include a Nutrition Facts label that lists pertinent information on the food product. This label will give you the breakdown of the macronutrients, such as proteins, fats and carbohydrates, contained in the food. Between the serving size grams and the grams of fats, you can easily calculate the percentage of fat by weight.

Instructions

• 1

  Look on the Nutrition Facts label for the serving size, listed in grams, and the grams of total fat.

• 2

  Divide the grams of total fat by the serving size to calculate the fat ratio. As an example, a 42 gram granola bar with 7 grams of total fat would have a fat ratio by weight of 0.167.

• 3

  Multiply the fat ratio by 100 to convert it into percentage format. In the example, 0.167 is converted into 16.7 percent fat, measured by weight.