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Last Updated on October 9, 2026

Trees You Can Tap for Syrup: Sap Sugar and Ratio by Species

You can tap any maple (sugar, black, red, silver, Norway and box elder), plus birch and black walnut. Sugar and black maple sap runs about 2 percent sugar, which takes about 43 gallons of sap for a gallon of syrup. Birch sap runs lower, mostly under 1 percent sugar, and Cornell’s three-season average ratio is about 100 gallons of sap for a gallon of syrup. The chart below shows each tree’s sap sugar, the sap-to-syrup math, when its season runs compared with sugar maple, and what the syrup tastes like.

Maple syrup can legally be made from any species in the genus Acer, though the flavor varies a lot between species (UVM Proctor Maple Research Center). Birch and black walnut each make their own distinctive syrup (Cornell Maple Program).

Trees you can tap: sap sugar, ratio, season and flavor

Sap per gallon of syrup uses the Rule of 86 (86 divided by the sap’s sugar percent), the same math as my Maple Sap to Syrup Calculator. Sugar percentages below are from Ohio State University Extension unless noted; season and flavor notes are Cornell’s unless noted. Where a source measured a real ratio, it is listed too.

Tree	Typical sap sugar	Gallons of sap per gallon of syrup	Season vs sugar maple	Flavor and notes
Sugar maple (Acer saccharum)	2% or higher	86 ÷ 2 = 43	The baseline	The classic. Yard trees with big open crowns give more and sweeter sap than forest trees.
Black maple (Acer nigrum)	Similar to sugar maple	About 43	Same; most producers treat the two as one species	Same quality sap as sugar maple.
Red maple (Acer rubrum)	Usually 1.5 to 2%	86 ÷ 2 = 43 to 86 ÷ 1.5 = 57	Breaks bud before sugar maple, so it ends sooner	Syrup more likely to be cloudy (Ohio State). Buddy sap after bud break gives off-flavored syrup (UNH).
Silver maple (Acer saccharinum)	Median 1.5%, tied with sugar maple in an Appalachian study (JAFSCD)	86 ÷ 1.5 = 57	One of the first to bud out, shorter season (Ohio State)	Syrup more likely to be cloudy (Ohio State).
Norway maple (Acer platanoides)	Sources disagree: lower than sugar maple (Penn State) or similar (Ohio State)	No published number; test your own sap	Not given in these sources	Non-native and considered invasive in some states (Ohio State).
Box elder (Acer negundo)	Median 1.2%, range 0.5 to 2.0% (JAFSCD)	86 ÷ 1.2 = 72	Blooms later than red and silver maple, as sugar maple does (JAFSCD)	Heavy, almost sorghum-like, a bit bitter; boil it apart from other maple sap (Ohio State).
Birch (paper, yellow and other birches)	0.8 to 1.5% (Alaska); 0.86% average over three seasons (Cornell)	86 ÷ 0.86 = 100; Cornell measured 104, Alaska says 110 or more	Starts about when maple season ends	Fruity-tart, notes of raspberry, cherry and molasses; darker than maple, better for cooking than pancakes.
Black walnut (Juglans nigra)	2 to 3.5% in spring, under 1% in fall, many trees 4 to 5% (Cornell)	86 ÷ 3.5 = 25 to 86 ÷ 2 = 43	Most trees tapped in late winter in Cornell’s trial	Tastes like maple with a nuttier flavor, but trees give far less sap, and pectin clogs filters.

The silver maple and box elder numbers come from a peer-reviewed study of 152 trees in south-central Appalachia, published in the Journal of Agriculture, Food Systems, and Community Development. Its authors note that sugar maple sap there tested lower than values commonly found farther north, so read these as one region’s numbers. In the same study, sugar maple and silver maple both had a median of 1.5 percent, and red maple 1.3 percent.

Gallons of sap per gallon of syrup, by the Rule of 86 (birch shows Cornell and Alaska measured ratios). The dark part of a bar is the sweetest typical sap; a light end shows how far the range runs. Norway maple is left off because no source gives a number.

The Rule of 86, shown

Divide 86 by your sap’s sugar percent, and you get the gallons of sap it takes to make one gallon of syrup. A 1956 University of Vermont Agricultural Experiment Station bulletin, Variation in Sugar Content of Maple Sap, walks through it: 86 gallons at 1 percent, 43 gallons at 2 percent, 22 gallons at 4 percent. Each time the sugar doubles, the sap you need is cut in half.

The rule is a rule of thumb. Researchers use refined versions with 87.1 or 87.5 in place of 86, and real birch ratios run a little past the rule: Cornell’s birch syrup page reports a 104 to 1 average over three seasons, and the University of Alaska Fairbanks Cooperative Extension says 110 gallons or more. On birch, plan for a bit more sap than the math says.

Sap Brix chart: what your refractometer reading means

A sap refractometer reads sugar as degrees Brix, and for sap, Brix and sugar percent are the same number for practical purposes. Find your reading in the chart below.

Sap Brix	Gallons of sap per gallon of syrup	Gallons per quart	Where you see it
0.5	172	43	Low end of birch (Cornell)
0.8	108	26.9	Birch: Alaska’s low end, near Cornell’s 0.86% average
1.0	86	21.5	Birch, inside Alaska’s 0.8 to 1.5% range
1.2	72	17.9	Box elder median (JAFSCD)
1.5	57	14.3	Red maple low end, silver maple median
2.0	43	10.8	Average maple sap (University of Minnesota)
2.5	34	8.6	Sugar maple (UVM yearly averages ran 2.5 to 3.2%), spring walnut
3.0	29	7.2	Sugar maple, spring walnut
3.5	25	6.1	Top of Cornell’s spring walnut range
4.0	22	5.4	Sweet individual trees (UVM, Cornell walnut)
5.0	17	4.3	Rare, very sweet trees (UVM)

Enter your own reading in the Maple Sap to Syrup Calculator to see your gallons.

Gallons per quart is the same math divided by 4. At 2 percent that is about 11 gallons of sap for a quart, in line with the 10 to 15 gallons per quart that University of Maine Cooperative Extension gives for maple sap.

How to read sap Brix

Use a sap refractometer. The Cornell Maple Program’s beginner’s notebook explains that sap (“low Brix”) and syrup refractometers each read only their own range, so a syrup refractometer gives a useless reading on sap.
Zero it with clean water first. In the Appalachian four-maple study, researchers zeroed the refractometer with deionized water and wiped it clean between trees.
Take the drop from the spout, not the bucket. The 1956 UVM bulletin tested sap at the spout because sap sitting in a bucket can separate into layers.
Read it in good light. Visual refractometers need it, and sunlight works best (Cornell).
Plug the number into the calculator with your gallons of sap to see the syrup you will get.

Test more than one tree, and more than once. The UVM bulletin, a survey of 4,500 trees, found sugar maples in the same stand often differ by 2 to 3 percent sugar, and a sweet tree stays sweet year after year. Sugar also starts low early in the season, rises to a peak, then falls. Sweeter sap takes less time and fuel to boil down, which matters when you boil the way I do, on a fire ring evaporator with sap from my sugar maples.

Before you tap something other than a sugar maple

Know the tree. Maples have opposite buds and branches. Utah State University Extension’s boxelder and Norway maple guide warns that London planetree has a classic maple leaf shape but is not a maple.
Birch: University of Alaska Fairbanks Extension says to tap trees 8 inches or more across, put only one tap in a birch each year, and skip trees along maintained roads, in dog yards, or anywhere the soil may be polluted. Birch sap is perishable: keep it below 41°F for no more than six days, or freeze it.
Birch season: Cornell explains birch sap flow is driven by root pressure, not freeze and thaw, so it usually waits until temperatures stay at 50°F or higher. Birch sap sugar is mostly fructose, which scorches easily, so watch the finish closely.
Black walnut: in Cornell’s 2014 walnut trial, trees gave the equivalent of 6 to 11 ounces of syrup per tap, against 32 to 64 ounces for maples. The sap is sweet; there is just much less of it.
Box elder: Ohio State University Extension says not to combine box elder sap with sap from other maples.
Red and silver maple: they bud out early, and UNH Extension warns that bud break makes buddy sap and off-flavored syrup. Utah State University Extension’s boxelder and Norway maple guide says that once the syrup tastes buddy, pull the spouts and let the tree heal over the taphole.

For how many taps a maple can carry at its diameter, see How Many Taps per Maple Tree? When you get to the end of the boil, the finishing temperature calculator and the hydrometer temperature correction calculator tell you when it is done.

Quick questions

What trees can you tap for syrup besides maple?

Birch and black walnut. The Cornell Maple Program says both can be tapped and each makes its own distinctive syrup. Birch sap is far less sweet than maple, mostly under 1 percent sugar, while black walnut sap is as sweet as maple but the trees give much less of it.

Can you tap a Norway maple for syrup?

Yes. Any species in the genus Acer can be used for maple syrup, according to the UVM Proctor Maple Research Center. Sources disagree on how sweet Norway maple sap is, so test yours with a sap refractometer and use the Rule of 86 to see how much you need.

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

About 100 gallons or more. Cornell measured an average of 104 gallons of birch sap per gallon of syrup over three seasons, and University of Alaska Fairbanks Cooperative Extension says it takes 110 or more.

Can you make syrup from box elder?

Yes. Box elder is a maple. In a south-central Appalachian study its sap had a median of 1.2 percent sugar, about 72 gallons of sap per gallon of syrup by the Rule of 86. Ohio State University Extension describes the syrup as heavy and almost sorghum-like and says not to mix box elder sap with other maple sap.

What is the Rule of 86?

Divide 86 by the sugar percent (Brix) of your sap to get the gallons of sap needed for one gallon of syrup. Sap at 2 percent takes 43 gallons, and sap at 1 percent takes 86. Each time the sugar doubles, the sap you need is cut in half.

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