How much sap makes your syrup?

What the numbers mean

Maple sap is mostly water with a little sugar, usually between 1.5% and 3%. Syrup is what is left when enough water has boiled off to bring the sugar up to about two thirds of the weight, so a sweeter sap needs far less boiling. The calculator answers the three questions a sugarmaker asks: how much sap for how much syrup, how much syrup the taps will give, and when to draw off.

The formulas

Jones’s Rule of 86 gives the gallons of sap needed for one gallon of syrup as 86 divided by the sugar percentage of the sap. It is attributed to C. H. Jones, and UNH Cooperative Extension prints it in its guide for beginners. The syrup from a batch is the sap divided by that ratio. The finishing temperature is the boiling point of water on the day plus a fixed offset: 7.1 °F for syrup at 66 °Brix (North American Maple Syrup Council) or 7.5 °F for the standard syrup used in New Hampshire and Vermont, 67 °Brix at 60 °F (UNH Extension). Our season estimate is taps times sap per tap, then the Rule of 86; the sap per tap is your own figure.

Worked example

You collect 100 gallons of sap that tests 2% sugar. The rule gives 86 ÷ 2 = 43 gallons of sap per gallon of syrup, so 100 gallons make 2.33 gallons, about 9.3 quarts. That fits University of Maine Extension’s 10 to 15 gallons of sap per quart. If the same sap were 3% sugar the ratio would fall to 28.7 and the batch would make 3.49 gallons: sap sweetness matters more than almost anything else. Twenty taps that give 10 gallons of sap each over the season make 200 gallons, or 4.7 gallons of syrup at 2% — about 0.23 gallon per tap, close to the 0.25 gallon Maine Extension gives for good practices.

Finishing: at sea level plain water boils at 212 °F, so syrup is done at 219.1 °F by the NAMSC offset or 219.5 °F by UNH’s. At 1,000 feet water boils near 210 °F, so the targets drop by the same amount.

Limits of these rules

• The rule is an approximation. It assumes a standard density of finished syrup and was used over a narrow band of sugar contents; sap well outside 1.5% to 3% (a few trees give much more) deserves a direct measurement. The popular “40 to 1” is only the average case.
• Two sources, two offsets. NAMSC uses 7.1 °F for 66 °Brix and UNH 7.5 °F for 67 °Brix; both are close to the same syrup. A thermometer is only as good as its calibration, so use the same one for the water and the syrup and confirm the density with a hydrometer or refractometer.
• Do not calibrate in sap. The Council says to boil plain water, not sap, for the reference reading. The reference moves with weather and elevation, even during a boil.
• Wrong density spoils syrup. NAMSC warns that below 66 °Brix syrup will likely mold and ferment, and above 68 it forms crystals. Federal rules require at least 66 percent soluble solids (21 CFR 168.140).
• Sap yield per tap is a range, not a promise. Maine Extension quotes 5 to 15 gallons of sap per taphole in an average season.

How much sap does it take to make a gallon of maple syrup?

It depends on how sweet the sap is. The Rule of 86, attributed to C. H. Jones, says to divide 86 by the sugar percentage of the sap. Sap at 2% sugar takes 86 ÷ 2 = 43 gallons; UNH Extension lists 34.4 gallons at 2.5% and 28.7 at 3%, and sap at 1.5% takes about 57.3. University of Maine Extension puts it at 10 to 15 gallons of sap per quart of syrup, which is 40 to 60 gallons per gallon. The familiar “40 to 1” is the middle of that range, not a constant.

What temperature is maple syrup done?

Syrup is done at a set number of degrees above the boiling point of plain water on the same day. The North American Maple Syrup Council says syrup at 66 °Brix boils 7.1 °F above the boiling point of water; UNH Extension uses 7.5 °F, which it ties to a density of 67 °Brix at 60 °F. At sea level, with water boiling at 212 °F, that is 219.1 °F or 219.5 °F. The calculator shows both offsets.

Why does the finishing temperature change from day to day?

Because the boiling point of water does. It drops with elevation, from 212 °F at sea level to about 210 °F at 1,000 feet and 208 °F at 2,000 feet on the Colorado State Extension table our altitude tools use, and it also moves with the weather: NAMSC notes it can be a few degrees higher on a clear day than when a low-pressure front moves through. That is why the Council tells sugarmakers to boil a small pot of plain water, not sap, near the evaporator for three minutes and read it with the same thermometer they use on the syrup.

What density should maple syrup be?

Federal rules require maple sirup to contain not less than 66 percent by weight of soluble solids from the sap (21 CFR 168.140). NAMSC calls 66 to 68 °Brix correct: below 66 it will likely become moldy and ferment, and above 68 sugar crystals form in the bottom of the container. UNH Extension describes 67 °Brix at 60 °F as the standard in New Hampshire and Vermont. Some states are stricter, so check your own rules if you sell syrup.

How much syrup does a tap make in a season?

University of Maine Extension gives an average full-season yield of 5 to 15 gallons of sap per taphole, up to 40 to 60 gallons under favorable conditions, and roughly 0.25 gallon of syrup per tap with good practices. As an example, 20 taps at 10 gallons each and 2% sap give 200 gallons of sap and 4.7 gallons of syrup. Year-to-year weather, tree size and how the sap is collected move this widely.

How do I measure the sugar content of sap?

With a sap hydrometer in a hydrometer cup, according to UNH Extension, or a refractometer. NAMSC adds that hydrometers for sap are calibrated differently from syrup hydrometers, so they are not interchangeable. One Brix is about 1 percent sugar (NAMSC). Sugar content varies by tree and through the season, so average several readings.

Sources: UNH Cooperative Extension, S. Roberge, “Maple Sugaring Tips for Beginners and Backyard Maple Sugar Producers” (2013); North American Maple Syrup Council, “When is it Syrup?”, supplement to the Maple Syrup Digest (June 2017); University of Maine Cooperative Extension, Bulletin 7036, “How to Tap Maple Trees and Make Maple Syrup” (updated 2025); U.S. FDA, 21 CFR 168.140 “Maple sirup” (eCFR); boiling points by elevation from Colorado State University Extension, as used in our canning altitude calculator. For the next steps in the kitchen see the candy temperature calculator, the high altitude baking calculator and the food shelf life calculator for how long syrup keeps.