In a 5-pound bag of granulated white sugar, there are approximately 11 1/4 cups. Different varieties of sugar may have more or less by volume. For example, the same 5-pound bag yields 18 3/4 cups when measuring confectioner's sugar and 12 1/2 cups when measuring brown sugar.
Different measurement preparations will also effect the number of cups extracted from a bag of sugar, such as sifting confectioner's sugar or packing brown sugar. If exact proportions are necessary and a given recipe offers ingredient weights, a small kitchen scale may be used to determine the correct amount of sugar to add.