Finishing is the moment of truth. Pull syrup too early and it's thin and can spoil. Boil it too long and it crystallizes in the jar, or scorches in seconds. The good news: with a thermometer, a little patience, and ideally a hydrometer, you can hit it right every time.
The target: 66 to 67 Brix
Finished maple syrup is about 66 to 67% sugar, measured in degrees Brix. The USDA minimum for maple syrup is 66 Brix.
| Density | What happens |
|---|---|
| Under 66 Brix | Thin syrup. Can ferment or grow mold in storage. |
| 66 to 67 Brix | Just right. Keeps well and pours well. |
| Over about 68 Brix | Too thick. Sugar crystals form in the jar. |
Method 1: Temperature
Syrup is finished at about 7°F above the boiling point of water. At sea level water boils at 212°F, so syrup finishes around 219°F. But the boiling point of water changes with your elevation and with the weather, so measure it:
- On boiling day, bring a pot of water to a full boil.
- Put your thermometer in and note the temperature. That's today's boiling point.
- Add 7°F. That's your finish temperature.
As a rough guide, water boils about 1°F lower for every 500 feet of elevation. Our Finish Point calculator does the math for you.
Use a candy or digital thermometer that reads to at least 220°F, and check it in boiling water first. A thermometer that reads a couple of degrees off will put your syrup off too.
Method 2: Hydrometer (most accurate)
A syrup hydrometer floats in a tall cup of hot syrup and shows its density. It's the tool most sugarmakers rely on.
- Fill a hydrometer test cup with syrup straight from the pot.
- Lower the hydrometer in gently and let it settle.
- Read the scale at the surface of the syrup.
Hydrometers are calibrated for a specific temperature. A hot test hydrometer is read at about 211°F, and a cold test at about 60°F. Most have a marked line showing where finished syrup should float. Read it at the temperature it's made for, or your reading will be off.
Method 3: Refractometer
A maple refractometer reads Brix from a few drops of syrup. Let the sample cool first, place it on the glass, and look through the eyepiece or read the display. It's quick and uses very little syrup, which makes it handy for small batches.
Finishing step by step
- Move to a smaller pot when the batch is a few degrees below your finish point. Smaller batches are easier to control. Many people finish indoors on the stove at this stage, since most of the water is gone.
- Turn the heat down and stir. Near the end, syrup foams up quickly and can boil over.
- Watch the thermometer closely. The last few degrees go fast.
- Check the density with your hydrometer or refractometer when you reach the finish temperature.
- Pull it off the heat as soon as it reads 66 to 67 Brix, and filter it while it's hot.
Tip: It's much easier to fix syrup that's slightly thin (boil a bit more) than syrup that's scorched. Go slow at the end.
Fixing syrup that's off
Too thin
Put it back on the heat and boil a little longer, checking the density again.
Too thick
Stir in a small amount of hot sap or water, a little at a time, until it reads 66 to 67 Brix.
Scorched
Lightly scorched syrup tastes burnt and usually can't be saved. Keep the heat moderate and never let the finishing pot run dry.
Grades and color
Grade A maple syrup is sorted by color and flavor: Golden with Delicate taste, Amber with Rich taste, Dark with Robust taste, and Very Dark with Strong taste. Syrup usually gets darker as the season goes on. Every class is the same quality; it just comes down to taste.
Ready for the next step? Read How to Filter Maple Syrup, or go back to How to Boil Maple Sap.