Wine ABV Calculator
Estimate a wine’s alcohol by volume from its starting and finishing specific gravity, plus the potential alcohol of the must.
How it works
ABV ≈ (OG − FG) × 131.25 · Potential alcohol ≈ (OG − 1) × 1000 × 0.131 (fermenting fully to 1.000)
Wine starts at a much higher gravity than beer because grape and fruit musts carry more sugar, and dry wines finish below 1.000 as the yeast consumes nearly all of it. Multiplying the gravity drop by 131.25 gives ABV just as in brewing. The potential alcohol figure shows the maximum you would reach if fermentation ran completely dry, which helps you decide whether to add sugar (chaptalise) or stop fermentation to leave sweetness.
Worked example
A must at 1.090 fermented to 0.995 dropped 95 points, so ABV ≈ (1.090 − 0.995) × 131.25 = 12.47%. Its starting sugar of about 22.5 °Brix had a potential alcohol near 11.8%.
Frequently asked questions
Why can wine finish below 1.000?
Alcohol is less dense than water, so a fully fermented, sugar-free wine reads under 1.000 on the hydrometer — often 0.990–0.996. That negative reading is normal and is included in the gravity drop.
What is potential alcohol?
It is the ABV you would get if the yeast fermented every gram of sugar down to 1.000. Comparing it to your actual ABV tells you how much residual sugar (and sweetness) is left.
How does this differ from beer ABV?
The formula is the same; wine just runs at higher starting gravities and lower finishing gravities, so a single wine calculation spans a much larger sugar drop and higher alcohol than a typical beer.
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Educational estimate for home winemaking. Please drink responsibly.