A box of confectioner's, or powdered, sugar is usually a 1 lb. box, or 16 ounces. Confectioner's sugar is available in 4x and 10x concentrations. Other sizes of sugar include 2 lb. bags, 4 lb. bags and 25 lb. bags.
Confectioner's sugar is a versatile sweetener that combines superfine sugar with another product, such as corn starch, which helps to keep it from sticking together. The sugar is available in several levels of fineness, with 10x being the highest. Confectioner's sugar is used mostly in baking, such as being the foundations for most cake frosting, and serving as toppings for pastries like doughnuts, waffles and French toast.