People calculate nutrition information for a variety of reasons: weight loss, weight gain, weight maintenance. It's a simple skill that can be done with a nutrition label and, in some cases, a calculator.
Things You'll Need
 Nutrition label
 Calculator
How to Calculate Nutrition Information

Know the conversions. One gram of carbohydrates has four calories. One gram of protein has four calories. One gram of fat has nine calories. One gram of alcohol has seven calories.

Use the label. Nutrition labels list the total calories and the calories from fat, but using the conversions allows you to calculate the number of calories from protein and carbohydrates. For example, if an item has 49 grams of carbohydrates, multiply 49 by 4 calories to get 196 calories from carbohydrates.

Find the percentage of calories from a nutrient. To do this, divide the calories from a nutrient (fat, for instance) by the total calories and multiply by 100. For example, if your favorite snack has 200 calories, with 50 calories from fat, you divide 50 by 200 to get .25; multiply this by 100 to get 25. That snack has 25 percent calories from fat.