In baking, as with much of cooking, the actual amounts of an ingredient don't matter much—it's the ratio of ingredients that matters. Think of bakers' percentages this way: The flour is equal to 100 percent. Every other ingredient is then expressed in terms of its ratio to the amount of flour. If, for example, you had a dough with 16 ounces of flour and 8 ounces of water and 0.32 ounces of salt, you'd say that the dough contains 50% water because the water weighs 50% of what the flour weighs. In baker's talk, that's called 50% hydration.