Once you know how many calories you’re eating in a day – and the total number of carbs, protein and fat you’ve eaten – it’s easy to calculate the percentage of calories you’ve eaten from fat, carbs and protein using just a calculator. Once you calculate these percentages, compare them with the Institute of Medicine’s recommendations to be sure you’re getting recommended amounts of each macronutrient.
The easiest and quickest way to determine your daily calorie intake – and carb, protein and fat consumption -- is by using an online nutrition tracker, such as Livestrong.com’s MyPlate, Myfitnesspal.com or the U.S. Department of Agriculture’s SuperTracker. All of these resources help you track your calorie, carb, protein and fat intake throughout the day. Although more time-consuming, you can also opt to keep a food journal and track your calorie, carb, protein and fat intake using food labels and online nutrition databases – such as the U.S. Department of Agriculture’s National Nutrient Database.
Calories per Gram
MedlinePlus reports that carbs and protein each provide 4 calories per gram, and fat contains 9 calories in each gram. For example, if you’ve eaten 65 total grams of dietary fat, you’ve consumed 585 calories from fat. If you’ve eaten 95 grams of protein, you’ve consumed 380 calories from protein, and if you’ve eaten 250 carb grams, you’ve consumed 1,000 calories from carbohydrates. Alcohol – in alcoholic beverages – provides 7 calories per gram, reports the McKinley Health Center.
Percentage of Calories
Once you know the number of calories you’ve eaten from carbs, protein and fat, you can determine the percentage of calories you’ve consumed from each of the three macronutrients. Divide the number of calories eaten from each nutrient by the total number of calories you’ve consumed that day. Using the previous example, divide the 1,000 calories you ate from carbohydrates by 1,965, which is your total daily calorie intake -- equaling about 51 percent of your intake from carbohydrates. To calculate the percent of calories from protein and fat, divide 380 by 1,965 – which equals about 19 percent – and divide 585 by 1,965, which is about 30 percent of your calories from fat.
The Institute of Medicine provides acceptable macronutrient distribution ranges (AMDR) for carbs, protein and fat. These AMDRs are 45 percent to 65 percent of calories from carbs, 10 percent to 35 percent from protein and 20 percent to 35 percent of total calories coming from dietary fat. After calculating the percentage of your calories from carbs, protein and fat, compare them with the Institute of Medicine’s AMDRs to make sure your calorie compositions fall within recommended ranges.