One pound of powdered sugar equals approximately 3 3/4 cups. This figure assumes the sugar is unsifted. In metric units, 1 kilogram is equivalent to 1,956 milliliters.
Not all types of sugar have the same volume per pound. For granulated sugar, 1 pound equals approximately 2 1/4 cups. The finer granules of powdered sugar create more volume. Sifting the powdered sugar before measuring will further increase the volume by introducing additional air. When reading recipes, it is vital to take careful measurements and to use the correct type of sugar. Powdered sugar is often referred to as confectioner's sugar in recipes.
Confectioner's sugar is made from regular granulated sugar that has been finely ground into powder. To prevent crystallization and lumping, 3 percent cornstarch is added to the sugar. A number followed by the letter "X" is sometimes displayed on the box or bag that confectioner's sugar comes in to correspond with the number of times the sugar was ground during the manufacturing process.