One cup of powdered sugar is 4.41 ounces, so there are 3.63 cups in a pound of powdered sugar. The calculation is 16 ounces divided by 4.41 ounces per cup. Sifted powdered sugar is 3.61 ounces per cup, so there are 4.4 cups in one pound of powdered sugar if it is sifted. Contrarily, granulated sugar is 7.1 ounces per cup, and packed brown sugar is 7.75 ounces per cup.