Brix to Potential Alcohol: The Full Conversion Chart
Potential alcohol is estimated by multiplying degrees Brix by a conversion factor between 0.55 and 0.60, so juice at 24 Brix predicts somewhere between 13.2 and 14.2 percent alcohol by volume depending on which factor you use. That spread of a full percentage point is not a rounding error, it reflects real differences in yeast strain, fermentation temperature, and how completely a must ferments dry. The chart below runs from 16 to 30 Brix in half-degree steps and lists specific gravity, sugar in grams per liter, and potential alcohol at both the 0.55 and 0.59 factors, so you can see the range rather than trusting one number.
How do you convert Brix to potential alcohol?
Multiply degrees Brix by a conversion factor, conventionally between 0.55 and 0.60. Juice at 22 Brix predicts 12.1 percent alcohol at the 0.55 factor and 13.0 percent at 0.59. That is the whole calculation.
Degrees Brix (°Bx) is a concentration measurement: one degree Brix equals one gram of sucrose per 100 grams of solution. In grape juice, effectively all of that dissolved solid is fermentable sugar, mostly glucose and fructose in near equal parts, which is why a sugar-concentration reading can stand in for an alcohol prediction at all.
The conversion factor is empirical rather than a physical constant. It bundles together the stoichiometry of fermentation, the fraction of sugar that yeast diverts into biomass and glycerol instead of ethanol, and evaporative losses during an open fermentation. Different references land on different numbers because they were fitted against different fermentations.
Brix to potential alcohol chart, 16 to 30 Brix
Potential alcohol is shown at both common factors so the uncertainty is visible rather than hidden. Specific gravity is calculated from Brix, and sugar concentration is expressed in grams per liter, which is the unit most lab reports use.
| Degrees Brix | Specific gravity | Sugar (g/L) | Potential ABV at 0.55 | Potential ABV at 0.59 |
|---|---|---|---|---|
| 16.0 | 1.065 | 170 | 8.8% | 9.4% |
| 16.5 | 1.068 | 176 | 9.1% | 9.7% |
| 17.0 | 1.070 | 182 | 9.4% | 10.0% |
| 17.5 | 1.072 | 188 | 9.6% | 10.3% |
| 18.0 | 1.074 | 193 | 9.9% | 10.6% |
| 18.5 | 1.076 | 199 | 10.2% | 10.9% |
| 19.0 | 1.079 | 205 | 10.5% | 11.2% |
| 19.5 | 1.081 | 211 | 10.7% | 11.5% |
| 20.0 | 1.083 | 217 | 11.0% | 11.8% |
| 20.5 | 1.085 | 222 | 11.3% | 12.1% |
| 21.0 | 1.087 | 228 | 11.6% | 12.4% |
| 21.5 | 1.090 | 234 | 11.8% | 12.7% |
| 22.0 | 1.092 | 240 | 12.1% | 13.0% |
| 22.5 | 1.094 | 246 | 12.4% | 13.3% |
| 23.0 | 1.096 | 252 | 12.7% | 13.6% |
| 23.5 | 1.099 | 258 | 12.9% | 13.9% |
| 24.0 | 1.101 | 264 | 13.2% | 14.2% |
| 24.5 | 1.103 | 270 | 13.5% | 14.5% |
| 25.0 | 1.106 | 276 | 13.8% | 14.8% |
| 25.5 | 1.108 | 283 | 14.0% | 15.0% |
| 26.0 | 1.110 | 289 | 14.3% | 15.3% |
| 26.5 | 1.113 | 295 | 14.6% | 15.6% |
| 27.0 | 1.115 | 301 | 14.9% | 15.9% |
| 27.5 | 1.117 | 307 | 15.1% | 16.2% |
| 28.0 | 1.120 | 314 | 15.4% | 16.5% |
| 28.5 | 1.122 | 320 | 15.7% | 16.8% |
| 29.0 | 1.124 | 326 | 16.0% | 17.1% |
| 29.5 | 1.127 | 332 | 16.2% | 17.4% |
| 30.0 | 1.129 | 339 | 16.5% | 17.7% |
Two thresholds in this table have consequences beyond the cellar. Wine finishing above 16 percent alcohol by volume moves into a higher federal excise tax class, and wine above 24 percent is taxed as distilled spirits rather than as wine. Late-harvest and fortified programs sitting near those lines are worth modelling before the fruit comes in, not after.
Why does the conversion factor vary?
Because the factor is fitted to real fermentations, and real fermentations differ. Published values commonly sit between 0.55 and 0.60, and some references cite factors as high as 0.64.
Four things move it. Yeast strain determines how much sugar carbon is routed into ethanol versus biomass and glycerol. Fermentation temperature affects both yeast efficiency and how much ethanol evaporates from an open-top. Nutrient status, particularly yeast assimilable nitrogen, changes how cleanly the population works through the sugar. And the finishing point matters: a wine taken to genuine dryness has converted more sugar than one stopped at 2 grams per liter of residual.
The practical answer is to stop treating the factor as a lookup and start deriving your own. A winery that records starting Brix and finished alcohol on every lot for two vintages has a house factor accurate to a tenth of a percent for its own yeast, its own temperatures, and its own fruit. That is a better number than any published chart, including this one, and it costs nothing but the discipline of recording both ends of every fermentation in the same place.
How does Brix relate to specific gravity?
They measure different things but track each other closely in grape juice, which is why the two are often used interchangeably. Brix is a concentration, grams of sucrose per 100 grams of solution, read with a refractometer or a Brix hydrometer. Specific gravity is a density ratio against water, read with a standard hydrometer.
The chart above converts between them using the standard polynomial approximation. A rough field version, dividing the specific gravity decimal by four, gets close in the range that matters: a gravity of 1.096 divided out gives roughly 24 Brix, and the table agrees at 23.0. Close enough to sanity check an instrument, not close enough to log.
The reason to care is that the two instruments fail differently. A refractometer needs two drops and works in the vineyard, which makes it the right tool for ripeness sampling. A hydrometer needs a full cylinder of clear sample and is unaffected by alcohol, which makes it the right tool once fermentation is running.
Why does the reading change once fermentation starts?
Because a refractometer measures refractive index, and ethanol has a different refractive index than sugar. As soon as yeast starts producing alcohol, the instrument is reading a mixture and reporting it as if it were all sugar, which inflates the number.
The error is not small. A fermenting must that a hydrometer reads as fully dry can still show several degrees Brix on a refractometer, which is exactly the situation where a winemaker concludes a fermentation is stuck when it has actually finished. Either switch to a hydrometer once fermentation is underway, or apply a correction formula designed for alcohol-bearing must, and be consistent about which one you use across a vintage.
This is the single most common source of bad fermentation data in small wineries, and it is entirely avoidable by recording which instrument produced each reading.
How do you get actual alcohol instead of potential?
Potential alcohol is a prediction made from the starting sugar. Actual alcohol is what the finished wine contains, and the two differ whenever fermentation does not go exactly to plan.
For cellar work, the drop between starting and finishing readings is a better estimate than the starting number alone, because a wine that finishes below zero Brix has fermented more sugar than its starting reading accounted for. Negative readings are normal at dryness: ethanol is less dense than water, so a dry wine reads below the zero point on a Brix hydrometer.
For anything that goes on a label or a tax return, neither calculation is sufficient. Alcohol content for those purposes has to come from an actual measured result, and the tolerance permitted between the labelled figure and the measured one is defined in federal labelling regulation. Calculated potential alcohol is a planning number, not a compliance number, and the distinction matters most for wines that finish near the 14 percent and 16 percent tax boundaries.
Frequently asked questions
What is the formula for converting Brix to potential alcohol?
Multiply degrees Brix by a conversion factor between 0.55 and 0.60. At the widely used 0.55 factor, 24 Brix predicts 13.2 percent alcohol by volume; at 0.59 the same juice predicts 14.2 percent. The factor is empirical, not a physical constant, which is why two published charts can disagree by a full percent on the same fruit.
How many Brix do you need for 14 percent alcohol?
Between 23.7 and 25.5 Brix, depending on which conversion factor you use. At 0.59 you need about 23.7 Brix; at 0.55 you need about 25.5 Brix. Most North American red wine picks land in the 24 to 26 Brix band for exactly this reason.
Why does my refractometer read wrong during fermentation?
A refractometer measures how much the liquid bends light, and ethanol bends light differently than sugar does. Once fermentation starts producing alcohol, the reading is inflated and no longer a true Brix value. Use a hydrometer for anything past the initial juice reading, or apply a correction formula built for alcohol-bearing must.
Is Brix the same as specific gravity?
No. Brix is a concentration, grams of sucrose per 100 grams of solution, while specific gravity is a density ratio against water. They track each other closely in grape juice, so the chart on this page lists both, but they are different measurements taken with different instruments.
Does the Brix to alcohol conversion factor differ for red and white wine?
Not because of color. The factor varies with yeast strain, fermentation temperature, nutrient status, and how completely the must ferments to dryness. Reds often appear to convert at a higher factor because they are usually picked riper and fermented warmer, not because red juice behaves differently.
How do you calculate actual alcohol instead of potential alcohol?
Potential alcohol assumes every gram of sugar ferments. Actual alcohol is calculated from the drop between your starting and finishing readings, so a wine that starts at 24 Brix and finishes at minus 1.5 Brix has fermented more sugar than the starting number alone suggests. For label and tax purposes the only number that counts is a measured alcohol result from an approved method, not a calculation.
What Brix reading means the grapes are ready to pick?
There is no single number. Brix sets the alcohol ceiling, but pick decisions also weigh titratable acidity, pH, seed and skin tannin ripeness, and the weather forecast. Brix is the one variable that is easy to measure daily, which is why it gets more attention than it deserves on its own.
The chart is a starting point, your own data is the answer
Every published Brix conversion is somebody else's fermentations averaged together. It is a fine place to start and a poor place to stay. The winery that knows its own factor knows what a 25.5 Brix pick will actually produce, which changes pick timing, blend planning, and whether a lot lands on the comfortable side of a tax boundary. Getting there requires nothing exotic: starting Brix and finished alcohol, recorded against the same lot, every time, for long enough to see the pattern.
That is harder than it sounds when readings live in a vineyard notebook, a lab sheet, and a cellar whiteboard. Solera keeps them on one record: the Vintage and Lab module holds every sample and reading against its lot, and the Cellar and Fermentation module plots the curve as the numbers come in, so the relationship between what you picked and what you made is visible without reconstructing it at the end of the year.