Maple syrup finishing temperature calculator
Water boils at 212.0°F. Draw off syrup at:
Near the finish, 1°F is about 2.5 °Brix. Too thin and syrup can spoil; too thick and it crystallizes — confirm with a hydrometer or refractometer.
How it works
The math behind it
Finished syrup at 66.0 °Brix boils 7.1°F (3.9°C) above the boiling point of water. For 66.9–67 °Brix — the Vermont and New Hampshire standard, and where most maple hydrometers' red line sits — add about 7.5°F (4.2°C).
"219°F" is only right when water boils at exactly 212°F. That happens at sea level on a standard-pressure day. Weather alone moves water's boiling point a degree or more, and near the finish 1°F is about 2.5 °Brix — so boil water (or watch raw sap at the back pan) with the same thermometer the day you finish.
The elevation estimate uses the standard atmosphere and the Antoine equation for water. It's a starting point, not a substitute for a same-day measurement and a hydrometer.
Reference
Three ways to tell syrup is done
| Method | Target | Good to know |
|---|---|---|
| Thermometer | Draw off at water's boiling point + 7.1°F (3.9°C) for 66.0 °Brix, or + 7.5°F for about 67 °Brix. | Fast, and works while you boil. Measure water's boiling point the same day: near the finish, 1°F is about 2.5 °Brix. |
| Hydrometer | Most maple hydrometers read true at 60°F; add about 0.05 °Brix per °F above that. Hot test: 66 °Brix syrup reads about 58 at 211°F. | The standard check before bottling. The red lines on most maple hydrometers are set for Vermont's 66.9 °Brix. |
| Refractometer | Reads °Brix directly to about ±0.2, with a few drops of syrup. | Precise and quick. Most aren't made for syrup hotter than 180°F, and sap and syrup refractometers are different tools. |
Under 66 °Brix
Thin syrup spoils (ferments or molds) more readily.
66.0–68.9 °Brix
The legal range in the US and Canada; Vermont's minimum is 66.9.
69 °Brix and up
Too thick: it can crystallize in the jar.
Correct a hydrometer reading with the hydrometer calculator, or read the full season plan in backyard maple syrup.
FAQ
Common questions
- What temperature is maple syrup done?
- 7.1°F above the temperature water boils at that day. At sea level on a normal day that's about 219°F, but higher elevations and low-pressure weather bring it down.
- Why is my thermometer reading different from 219?
- Water rarely boils at exactly 212°F. Measure it the same day with the same thermometer, then add 7.1°F.
- Is temperature alone enough?
- It gets you close. Confirm density with a hydrometer or refractometer before bottling — thin syrup can spoil, and syrup above 68.9 °Brix can crystallize.
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