My syrup is too thin. Can I reboil it?

Yes. Bring it back to a boil and finish by temperature (about 7.1 °F above water's boiling point for 66.0 °Brix) and hydrometer. Expect new niter to form once it passes about 195–200 °F, so filter again before packing.

My syrup is too thick. Do I just add water?

Yes, clean hot water, stirred in, then re-check the density and reheat to at least 180 °F before packing. The tool gives the amount; for 70 °Brix syrup it is a little under half a cup per gallon.

What density should I aim for?

66.9 °Brix is the safe middle of the legal range and the Vermont minimum; 66.0 is the legal floor in the US and Canada. Above 68.9 the manual warns of crystals.

Calculator · volume × Brix

Maple Syrup Too Thin or Too Thick? Density Fix Calculator

Enter how much syrup you have and its temperature-corrected density. Thin syrup gets a boil-off figure; thick syrup gets the water to stir in before you reheat and pack.

Syrup you have

gal

Its density (corrected to 60 °F)

°Brix

Hydrometer cold test or refractometer reading, after the temperature correction.

Target

Units

Too thin: boil off

0.22gal of water

5.00 gal at 64.0 °Brix becomes 4.78 gal at 66.9 °Brix

Bring it back to a boil and finish by temperature and hydrometer; syrup under 66 °Brix can ferment or mold in the jar. How to finish →

Solids are conserved: volume × Brix stays constant, with the small change in density ignored. Hydrometer readings must be temperature-corrected first: use the correction tool.

How it works

The math behind it

Finished maple syrup must be 66.0 to 68.9 °Brix in the US and Canada (Vermont and New Hampshire require at least 66.9). Below that it can ferment or grow mold in the jar; above about 68.9 °Brix the 2022 Producers Manual says it tends to crystallize.

The arithmetic is a solids balance: the sugar does not go anywhere, so volume times Brix stays constant. Thin syrup at 64 °Brix needs about 4 percent of its volume boiled off to reach 66.9; thick syrup at 70 °Brix needs about 4.6 percent of its volume in water stirred in. The small change in syrup density between those points is ignored, which keeps the error well under a tenth of a Brix.

Measure before you fix. Hydrometers are calibrated at 60 °F and read low when hot, so correct the reading first; a refractometer reads directly. After thinning, reheat to at least 180 °F before packing (hot-pack rule); after re-boiling, finish by temperature and re-check.

FAQ

Common questions

My syrup is too thin. Can I reboil it?: Yes. Bring it back to a boil and finish by temperature (about 7.1 °F above water's boiling point for 66.0 °Brix) and hydrometer. Expect new niter to form once it passes about 195–200 °F, so filter again before packing.
My syrup is too thick. Do I just add water?: Yes, clean hot water, stirred in, then re-check the density and reheat to at least 180 °F before packing. The tool gives the amount; for 70 °Brix syrup it is a little under half a cup per gallon.
What density should I aim for?: 66.9 °Brix is the safe middle of the legal range and the Vermont minimum; 66.0 is the legal floor in the US and Canada. Above 68.9 the manual warns of crystals.

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