You can totally substitute brown sugar for white sugar! The ratio is 1:1 so this means whatever amount of brown sugar your recipe calls for, replace it with an equal amount of white sugar. However, expect the end result to have a less intense flavor and perhaps be slightly drier. Brown sugar has that pleasant caramel aroma and the molasses will add some moisture which white sugar doesn't have. A closer substitution would be to try some of these combinations: 1 Cup of granulated sugar + 1 tablespoon of molasses = 1 Cup of brown sugar 1 Cup of granulated sugar + 1 tablespoon of honey or maple syrup = 1 Cup of brown sugar