Understanding Brix, Specific Gravity and Baumé in Winemaking
When making wine, measuring sugar is one of the easiest ways to understand what is happening in your juice or must. Sugar levels help you estimate potential alcohol, decide whether fruit is ripe enough to ferment and monitor fermentation progress.
The three most common scales are Brix, Specific Gravity (SG) and Baumé. They all measure sugar concentration in different ways.
What is Brix?
Brix measures the approximate percentage of dissolved sugar in a liquid by weight.
For example, juice at 20° Brix contains roughly 20 grams of sugar per 100 grams of juice.
Brix is commonly used when testing grape juice before fermentation. A refractometer is often used for quick Brix readings because it only needs a few drops of juice.
As a general guide:
- 16 to 18 Brix: lighter, lower-alcohol wine potential
- 20 to 23 Brix: common range for many table wines
- 24+ Brix: higher potential alcohol and potentially riper fruit character
The ideal reading depends on grape variety, wine style, acidity and the alcohol level you want to achieve.
What is Specific Gravity?
Specific Gravity, or SG, compares the density of your juice or wine with water.
Pure water has an SG of 1.000. Grape juice with dissolved sugar is heavier than water, so its reading is higher. For example, juice may start at 1.085 or 1.095 before fermentation.
As yeast converts sugar into alcohol, the specific gravity falls. Finished dry wine can be close to 1.000 or slightly below it because alcohol is less dense than water.
A hydrometer is the most common tool for measuring SG during fermentation.
What is Baumé?
Baumé, sometimes written as Bé, is another scale used to estimate sugar levels and potential alcohol in grape juice.
It is often used by winemakers in Australia and Europe. In winemaking, higher Baumé generally means higher sugar and higher potential alcohol.
As a broad guide:
- 10° Baumé: around 10% potential alcohol
- 12° Baumé: around 12% potential alcohol
- 14° Baumé: around 14% potential alcohol
Baumé is useful, but it remains an estimate. Final alcohol depends on yeast performance, fermentation conditions and how much sugar is actually fermented.
How Brix, SG and Baumé relate
All three scales are trying to answer a similar question: how much sugar is in the juice?
A rough comparison looks like this:
|
Brix |
Specific Gravity |
Baumé |
Approximate Potential Alcohol |
|---|---|---|---|
|
18 |
1.074 |
9.5 |
10% |
|
20 |
1.083 |
10.5 |
11% |
|
22 |
1.092 |
11.5 |
12% |
|
24 |
1.101 |
12.5 |
13% |
|
26 |
1.110 |
13.5 |
14% |
These figures are guides only. The exact conversion can vary depending on the calculator, measurement method and composition of the juice.
Which scale should you use?
Use the scale that suits your equipment and recipe.
- Use Brix if you are checking fresh grape juice with a refractometer.
- Use SG if you are using a hydrometer to track fermentation.
- Use Baumé if your recipe, winemaking guide or local grape supplier uses the Baumé scale.
The most important thing is consistency. Record your readings at the start of fermentation and again at the end so you can understand how your wine developed.
Important note about refractometers after fermentation starts
A refractometer works very well before fermentation because sugar is the main dissolved substance in the juice.
Once alcohol is present, it affects how light moves through the sample. This means the refractometer reading needs correcting to estimate the true remaining sugar or final gravity.
For post-fermentation readings, use a hydrometer or a refractometer correction calculator.
Frequently asked questions
Is Brix the same as sugar percentage?
Brix is an approximation of dissolved sugar percentage by weight. It is very useful for grape juice, but juice also contains acids, tannins and other compounds that can affect the reading slightly.
Which is more accurate: hydrometer or refractometer?
A refractometer is convenient before fermentation. A hydrometer is generally more reliable for measuring fermentation progress and final gravity after alcohol is present.
What Baumé should grapes be for wine?
Many table wines are made from grapes around 11 to 14° Baumé, depending on style, grape variety and desired alcohol level.