Powdered sugar, also known as icing sugar or confectioners sugar, is granulated sugar that has been crushed into a fine white powder. The sugar often is added to frosting and dessert recipes. It contains cornstarch which prevents it from forming lumps, but the cornstarch can cause a recipe to thicken. When you run out of granulated sugar, you can substitute powdered sugar to your recipe if thickening will not ruin the taste and texture.
Look at the recipe to determine how much granulated sugar you will need.
Substitute 1 3/4 cups of packed powdered sugar for every 1 cup of granulated sugar.
Add the sugar according to the recipe.