Rule of 87
Divide the sugar content of your sap into 87 to find out how many gallons of sap it will take to make one gallon of Pure Maple Syrup.
Example: Sugar Content = 2.5
87 divided by 2.5 = 34.8 gallons
It will take 34.8 gallons of sap to make one gallon of Pure Maple Syrup from 2.5 percent maple sap.