Our recipe here is for 1 serving (a little over 7 ounces). There are 128 ounces in a gallon and 128 divided by 7 would be about 18. So if you multiplied all of the ingredients in our recipe by 18 you should have about a gallon. For one gallon, I would use: 54 ounces apple cider 36 ounces bourbon 2 ounces lemon juice 36 ounces ginger beer Mix the cider, bourbon, and lemon juice ahead of time and keep in the fridge to stay cold. Wait to add the ginger beer until you’re just about to serve it—if you add it too far ahead of time, it will go flat. To serve, pour into glasses filled with fresh ice.