Boiling cider evaporates the water in much the same way as how maple syrup is made, and the final product will be ⅛ of the original volume. So, a ½ gallon of fresh cider will give you about 1 cup of apple syrup and will take about 3 to 4 hours to make. You can also double the recipe to one gallon which will yield about 2 cups and will take 5 to 6 hours to reduce.