Knowing the number of calories you eat from sugar can help you when working to lose weight or when trying to control your blood sugar. If you regularly add sweeteners, such as granulated sugar or brown sugar, to foods or beverages, it's important to know how many calories this contributes to your daily intake. You can also compare the number of calories you're consuming from sugar to recommended guidelines for sugar intake.
Measure the amount of sugar you are adding to your food or beverage to determine the total number of teaspoons. For reference -- one tablespoon equals 3 teaspoons and 1/8 cup is 6 teaspoons. One cube of sugar is about 1/2 teaspoon and a single sugar packet is about 2/3 teaspoon.
Multiply the number of teaspoons by 4 to get the total grams of sugar, because there are 4 grams of sugar per teaspoon of granulated sugar, according to the U.S. Department of Agriculture.
Multiply the total grams of sugar from step 2 by four to get the total calories from sugar, because there are 4 calories per gram of sugar. For example, there are 32 calories in 8 grams of sugar, which equals 2 teaspoons.