Brown sugar is just white sugar that either retained residual molasses during refinement, or had molasses added after it had been processed. Brown sugar can be substituted directly, in the same quantities, as white sugar in most brownie recipes. Some recipes specifically call for brown sugar instead of white sugar. The only difference will be in flavor -- brownies made with brown sugar will have a slight molasses flavor, especially if you pack the sugar when you measure it.

If your goal is a sugar-free version of brownies, swap out the standard sugar for a dry sugar substitute. Dry sugar substitutes, such as zero-calorie sweeteners made with sucralose, aspartame or stevia, can be swapped in your brownie recipes. Most sugar substitutes can be swapped in equal quantities with granulated sugar, but check the instructions on the package.

Several wet sugar substitutes can also replace the granulated sugar in brownies. Maple syrup and honey can both replace sugar, though using them won't cut calories. If you want to go sugar-free, try a zero-calorie liquid sweetener. Agave nectar can replace a portion of white sugar at a ratio of about 2/3 cup agave for every 1 cup of granulated sugar. When using wet substitutes, reduce other wet ingredients to avoid a runny batter. Removing one egg white is usually enough.

If you are in a pinch, or if you are feeling creative, think outside the box for adding sweetness to brownies. Unsweetened dried fruit purees are an excellent source of natural sweetness. You can pulse your own purees in a food processor or buy fruit purees in the baking section of the grocery store. Swap out one-half of the oil or butter in your brownie recipe with a fruit puree, like prunes, and likewise cut the sugar in half. If the recipe calls for granulated sugar, try half as much brown sugar or sugar substitute instead.