As noted earlier, the sap is very sweet this season. We have had brix readings of 4.1 and 3.9. The question is how much sap at a given brix reading is needed to produce one gallon of syrup? The Rule of 86 can help us. Its not exact, but its close enough for general work. Here is the rule: S=86/X where “S” is the amount of raw sap to make one gallon of finished syrup and “X” is the brix reading of the raw sap. So if we use our brix reading of 3.9, we get S=86/3.9, or S=22 gallons of raw sap to make one gallon of finished syrup. We usually say it takes 40 gallons of sap to make one gallon of syrup, a brix reading of about 2.1. So sap with a 3.9 brix is very sweet sap and only takes 22 gallons of sap to make one gallon of syrup; that is a significant improvement. Here is a link to the North American Maple Syrup Producers Manual with more background on the Rule of 86 .