How to use the maple sap to syrup calculator
- Enter the sugar content of your sap in percent Brix, measured with a refractometer or hydrometer.
- Enter how much syrup you want and choose US gallons or liters.
- Open the advanced options if you want a different rule constant than 86.
- Read the sap you need, the ratio and the water to boil off.
Formula
Sap per unit of syrup = 86 / sugar percent
Sap needed = ratio x syrup wanted
Water to boil off = sap - syrup
The rule of 86 assumes finished syrup near 66% sugar. Some producers use 87 or 87.1, which you can enter.
Sap at 2% sugar
Sap with 2% sugar needs 86 / 2 = 43 parts of sap for 1 part of syrup. To make 1 gallon of syrup you need 43 gallons of sap and boil off 42 gallons of water.
Sweeter sap saves a lot of work: at 3% the ratio is 28.7 to 1, and 4 liters of syrup from 2.5% sap takes 137.6 liters. With a rule constant of 87 at 2% the ratio is 43.5 to 1.
Why sugar content decides the work
Maple syrup is sap with most of the water boiled away. Sap holds only a small amount of sugar, usually between 1.5% and 3%, and syrup is about 66% sugar, so the amount of sap needed depends on how sweet it is. A drop from 2.5% to 2% sap raises the sap needed per gallon of syrup from about 34 gallons to 43.
That is why producers choose trees with sweeter sap and measure it. The rule of 86 is a quick way to turn a reading into an estimate. It is a rule of thumb, and the true ratio depends on the density of the finished syrup.
Planning a boil
Knowing the water to boil off helps you plan fuel, time and pan size. Evaporating dozens of gallons takes hours and a lot of heat, which is why many people boil outdoors. Sap also spoils if left warm, so collect and store it cold and boil it soon.
Sugar content changes through the season, usually falling as the weather warms, so measure again during the run. The page gives an estimate, and the finished syrup is judged by its density or temperature on the day.
Assumptions and limits
- The rule constant is 86 unless you change it, and sugar content is in percent Brix.
- Volumes use the same unit for the sap and the syrup.
- Evaporation losses to steam are not separate from the water boiled off.
- Nothing is uploaded.
Frequently asked questions
Why 86?
It comes from dividing a number close to 86 by the sap sugar percent, based on the sugar content of finished syrup. It is a long-used rule of thumb.
What sugar content should I expect?
Sap commonly lies between 1.5% and 3% and varies by tree and day. Measure yours rather than relying on a general figure.
Does this tell me when the syrup is done?
No. It estimates how much sap you need. Finished syrup is judged by density or by its boiling temperature above that of water.
Can I use liters?
Yes. Choose liters and all the amounts are in liters.