Alcohol By Volume
From BrewWiki
Alcohol By Volume (ABV) is simply a measure of the percentage of alcohol as measured by a percentage of the total volume of the beer. This is equivalent to the proof value of higher alcohol liquors. Beer typically has an alcohol by volume value of between 3 and 8%. Barley wine may have an ABV as high as 10% or more. To calculate the approximate alcohol by volume, simply measure the original gravity and final gravity as a 3 digit specific gravity and apply this formula:
- ABV = (Orig_gravity - Final_gravity) * 131