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

About 43 gallons of 2% sugar-maple sap for one gallon of syrup. Sweeter sap takes less: 3% sap needs about 29 gallons, 4% about 21.

Is the 40:1 rule accurate?

40:1 is a round rule of thumb for sap around 2.1–2.2% sugar. Measure your sap sugar and the ratio can swing from 30:1 to well over 60:1.

Do I need to measure sugar content?

It helps a lot. A sap refractometer or sap hydrometer costs less than a tank of propane and tells you how long you'll be boiling.

Maple Sap to Syrup Calculator

Enter how much sap you collected and its sugar content. You'll get the sap-to-syrup ratio, how much syrup to expect, and how much water you'll be boiling off.

Units

Sap collected

gal

Sap sugar content

°Brix

Read it with a sap refractometer or sap hydrometer. Not sure? Sugar maples average about 2–2.5%.

Finished syrup density

66.0 is the US & Canadian minimum; Vermont and New Hampshire require 66.9.

Formula

Syrup you'll make

2.31gal

≈ 9.3 quarts

Sap-to-syrup ratio

43.2 : 1

43.2 gal of sap per gal of syrup

Water to boil off

97.7gal

That's 98% of what you collected — plan your fuel and boil time around it.

How it works

The classic Jones Rule of 86 says it takes 86 ÷ (sap sugar %) units of sap to make one unit of syrup — so 2% sap needs about 43 gallons per gallon of syrup. It dates to 1946 and assumed syrup at 65.5 °Brix, a little thinner than today's standard.

The University of Vermont's Proctor Maple Research Center revised it in 2013: 87.1 ÷ sugar − 0.32 for 66.0 °Brix syrup (the US and Canadian minimum) and 88.2 ÷ sugar − 0.32 for 66.9 °Brix (the Vermont and New Hampshire standard). The revised rule is the default here.

Because it's a volume ratio it works the same in litres or imperial gallons. Above about 8 °Brix — reverse-osmosis concentrate — both rules get less accurate. Real batches come out a bit lower than the math because of syrup left in pans and filters.

Sources

The “Jones Rule of 86” Revisited — UVM Proctor Maple Research Center (Perkins & Isselhardt, 2013)
North American Maple Syrup Producers Manual, 2nd ed. (Bulletin 856) — The Ohio State University Extension
Maple Syrup Production Beginner's Notebook — Cornell Maple Program

More sugaring tools

Finishing temperature →
Water's boiling point + 7.1°F — worked out for today.
Hydrometer correction →
Correct any reading to 60°F and check your density.
Taps per tree →
Measure the trunk, get a safe tap count.

Common questions

How much sap does it take to make a gallon of maple syrup?: About 43 gallons of 2% sugar-maple sap for one gallon of syrup. Sweeter sap takes less: 3% sap needs about 29 gallons, 4% about 21.
Is the 40:1 rule accurate?: 40:1 is a round rule of thumb for sap around 2.1–2.2% sugar. Measure your sap sugar and the ratio can swing from 30:1 to well over 60:1.
Do I need to measure sugar content?: It helps a lot. A sap refractometer or sap hydrometer costs less than a tank of propane and tells you how long you'll be boiling.

Your whole season, logged

LuckySap keeps every collection and boil in one place — sap totals, sugar readings, sap-to-syrup ratios, and a season you can compare next year. Free on iPhone.