Brix to Potential Alcohol

It's one of the commonly cited approximations winemakers use to relate Brix sugar content to potential alcohol, typically expressed as a range around 0.55 to 0.64 depending on the source and the fermentation efficiency assumed. This calculator uses 0.59, a figure toward the middle of that widely used range, as a general-purpose estimate rather than a laboratory-derived constant for your specific must.

It's the percentage of available sugar your yeast strain will realistically convert to alcohol before it stops fermenting, whether from reaching its alcohol tolerance, running out of nutrients, or simply finishing the job. Most wine yeast strains achieve somewhere between 90% and 100% attenuation under good conditions; lower values leave more residual sugar and produce a sweeter, lower-alcohol wine.

Because attenuation almost never reaches a literal 100% in practice — some sugar is typically left unconverted even in a strong, healthy fermentation. This calculator computes residual sugar directly from the gap between full potential sugar and what your entered attenuation percentage actually converts, so any attenuation below 100% leaves some measurable sugar behind.

No — this is a planning estimate for before or early in fermentation, not a substitute for tracking specific gravity with a hydrometer or refractometer as fermentation actually progresses. Real attenuation depends on yeast strain, nutrient levels, temperature, and the must's own alcohol tolerance ceiling, none of which this calculator measures directly.

The Sweetness Level is derived from residual sugar, which depends on both Brix and yeast attenuation together — lowering attenuation while holding Brix constant leaves more sugar unconverted, which can shift the wine from Dry into Off-Dry or Sweet territory even without changing the starting sugar content.