Figuring out how close I am to syrup

[Jwolverton03]

I’ve got a batch that I got to 25-30 brix, and I pulled it and stuck it in the fridge overnight. Probably about 5 gallons worth or so. My question is, how do I figure out how much syrup to expect out of that 5 gallons?

[Keitha333]

https://organicbackyardgardening.com/maple-sap-to-syrup-calculator/

[DRoseum]

Adjusted rule of 86...

Sap to make 1 gallon of syrup = [(88.2 / % brix) - 0.32]

So expected syrup = volume of sap you have / volume needed

88.2/25% - 0.32 = 3.2 sap needed

5/3.2 = 1.55 gallons expected at 66.9 target brix.