How Do I Change Percentage of Fat Into Number of Fat Grams?

You need to know the nutrition in food if you are to make good diet decisions, such as how much fat to eat. The Mayo Clinic recommends eating no more than 70 grams of fat per day on a 1,800-calorie diet. You can determine the number of grams of fat in a serving of food, or the number of grams of fat permissible in your diet, if you know the total calories and the percentage of those calories that are comprised of fat. A gram of fat contains about nine calories. Knowing this, it's a simple matter to make the conversion.

Things You'll Need

• Calculator

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Instructions

• 1

  Divide the percentage of fat by 100. This converts the percentage to a decimal fraction. For example, if the percentage of fat was 40, divide 40 by 100, which would equal 0.40.

• 2

  Multiply the number you obtained in Step 1 by the total number of calories. This gives you the number of calories from fat. In the example in Step 1, if the total number of calories in a serving is 300, then 0.40 x 300 = 120 calories of fat per serving.

• 3

  Divide your answer from Step 2 by a factor of 9 calories per gram of fat. This is the approximate number of grams of fat. In the example, 120/9 = 13.33 grams of fat.