How to Find the Percentages of Carbohydrates

Carbohydrates should comprise 45 to 65 percent of your daily calories

Carbohydrates should comprise 45 to 65 percent of your daily calories

Carbohydrates, your body’s main energy source, provide four calories per gram. Knowing this you can calculate the percentage of carbohydrate in any food, if you also know the total grams of carbohydrate in that food and the calories it contains. This information is found on the nutrition facts label, present on most foods. Determining the carbohydrate percentages in the foods you eat can help ensure that you meet your daily carbohydrate requirement.

How to Calculate the Carbohydrate Percentage

The total calories a food contains is listed near the top of the nutrition facts label, with grams of carbohydrate several lines underneath. To calculate the percentage of carbohydrate, take the grams of carbohydrate listed and multiply it by four. The result is the number of calories supplied by carbohydrate in that food. Divide this by the total calories and then multiply by 100 to convert the answer to a percent.

A Sample Calculation

Take for example a calculation using a 90-calorie slice of whole-wheat bread with 15 grams of carbohydrate. First multiply 15 by four, which yields 60 calories from carbohydrates. Next, divide this by 90 calories which equals .667. To convert this to a percentage, multiply by 100, or 66.7 percent carbohydrate.

What is Daily Value?

Daily Value, or DV, is also found on the nutrition facts label. Note that the percent carbohydrate is different than the percent DV, found to the right of the carbohydrate grams on the label. DV refers to a 2,000-calorie diet, the average daily adult intake. Your calorie needs may vary, depending upon your age, health, weight and activity level. For carbohydrates, 100 percent DV equals 300 grams, so the DV for carbohydrates tells the percentage of 300 grams that the food contains. For example, if a food label reads 50 percent DV, that food would contain 150 grams carbohydrate.

Importance of Carbohydrates

According to the Institute of Medicine, 45 to 65 percent of your daily calories should be provided by carbohydrates, with a 130-gram minimum. A common misconception is that a carbohydrate-rich diet will cause weight gain. But glucose, a simple carbohydrate, is the sole fuel source that your brain and nervous system use. Skimp on the carbohydrates in your diet and chances are you will end up feeling tired, sluggish and irritable because your brain lacks the kind of fuel it depends upon.

Choose Wisely

Not all carbohydrates are equally nutritious. Refined carbohydrates such as white breads, rice and pastas have many nutrients stripped away during processing. To maximize your overall vitamin, mineral, fiber and antioxidant intake, choose whole-grain varieties. Fruits and vegetables are also good carbohydrate sources, so make these, along with whole grains, the mainstay of your diet.

About the Author

Sue Roberts began writing in 1989. Her work has appeared in such publications as “Today’s Dietitian” and "Journal of Food Science." Roberts holds a Bachelor of Science in nutrition from Pennsylvania State University, a Master of Public Health in nutrition from the University of Minnesota and a Master of Science in food science from Michigan State University. She is a registered dietitian and certified nutritionist.

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