We just were thinking about the rule of 86 or 87 depending on if you are in VT or not. To figure how much sap makes a gallon of syrup you divide 87 by your sugar content. Simple, 2%sap 86/2 it takes 43 gallons of sap to make a gallon of syrup. Well we have 100 gallons of 12% sap and wanted to know how much syrup we will have when we are done. Rule of 86 is 86/12 =7.25 100 gallons 100/7.25 = 13.79 gallons of syrup. Here is where I get confused. If I have syrup at 66% sugar then the rule of 86 would say it takes 1.3 gallons of syrup to make a gallon of syrup. This makes no sense. Can some one clear this up? Thanks