Alcohol by volume
Alcohol by volume (abbreviated as ABV, abv, or alc/vol) is a standard measure of how much alcohol (ethanol) is contained in an alcoholic beverage (expressed as a percentage of total volume). The ABV standard is used worldwide.
Typical levels 
Details about typical amounts of alcohol contained in various beverages can be found in the articles about individual drinks.
|Fruit juice (naturally occurring)||less than 0.1%|
|Chicha||1%–11% (usually 1%–6%)|
|Beer||2%–12% (usually 4%–6%)|
|Barley wine (strong ale)||8%–15%|
|Wine||9%–16% (most often 12.5%–14.5%)|
|Sake (rice wine)||15% (or 18%–20% if not diluted prior to bottling)|
|Fortified wine||15.5%–20% (in the European Union, 18%–22%)|
|Soju||17%–45% (usually 19%)|
|Shochu||25%–45% (usually 25%)|
|Mezcal, Tequila||32%–60% (usually 40%)|
|Vodka||35%–50% (usually 40%)|
|Brandy||35%–60% (usually 40%)|
|Whisky||40%–55% (usually 40% or 43%)|
|Pálinka||42%–86% (legally in Hungary 48%–51%)|
|Ţuica||45%–60% (usually 52%)|
|Neutral grain spirit||85%–95%|
Alcohol proof 
Another way of specifying the amount of alcohol is alcohol proof, which in the United States is twice the alcohol-by-volume number, while in the United Kingdom it is 1.75 times the number (expressed as a percentage). For example, 40% abv is 80 proof in the US and 70 proof in the UK. However, since 1980, alcoholic proof in the UK has been replaced by abv as a measure of alcohol content.
Proof and alcohol by weight 
In the United States, a few states regulate and tax alcoholic beverages according to alcohol by weight (abw), expressed as a percentage of total mass. Some brewers print the abw (rather than the abv) on beer containers, particularly on low-point versions of popular domestic beer brands.
At relatively low abv, the alcohol percentage by weight is about 4/5 of the abv (e.g., 3.2% abw is equivalent to 4.0% abv). However, because of the miscibility of alcohol and water, the conversion factor is not constant but rather depends upon the concentration of alcohol. 100% abw, of course, is equivalent to 100% abv.
Calculation of alcohol content 
During the production of wine and beer, yeast is added to a sugary solution. During fermentation, the yeast organisms consume the sugars and produce alcohol. The density of sugar in water is greater than the density of alcohol in water. A hydrometer is used to measure the change in specific gravity (SG) of the solution before and after fermentation. The volume of alcohol in the solution can then be calculated.
The calculation for beer is:
Where 1.05 is the number of grams of ethanol produced for every gram of CO2 produced, and .79 is the density of ethanol,
However, many brewers use the following formula:
See also 
- "Lafayette Brewing Co.". www.lafayettebrewingco.com. Retrieved 2012-02-04.
- "Glossary of whisky and distillation". www.celtic-whisky.com. Retrieved 2012-02-04.
- "English Ales Brewery Monterey British Brewing Glossary". www.englishalesbrewery.com. Retrieved 2012-02-04.
- "Joseph Louis Gay-Lussac (1778–1850)". chemistry.about.com. Retrieved 2008-07-05.
- Robinson, Jancis. The Oxford Companion to Wine, 3rd edition, (Oxford University Press: 2006). See alcoholic strength at p. 10.
- Robinson, Jancis. The Oxford Companion to Wine, 3rd edition, (Oxford University Press: 2006). See fortification at p. 279.
- C.J.J. Berry, 1987, First Steps in Winemaking, eighth edition, Special Interest Model Books Ltd, printed in UK
- Regan, Gary (2003). The Joy of Mixology. New York: Clarkson Potter. pp. 356–357. ISBN 0-609-60884-3.
- "Realbeer.com: Beer Break - Alcohol Content In Beer". www.realbeer.com. Archived from the original on 4 July 2008. Retrieved 2008-07-05.
- Berry, C.J.J. (1987). First Steps in Winemaking. Poole, United Kingdom: Special Interest Model Books.
- Anon, 2012, Industrial Microbiology Beer Fermentation Practical, School Of Applied Sciences, RMIT University, Melbourne
- Hehner, Otto (1880). Alcohol Tables: giving for all specific gravities, from 1.0000 to 0.7938, the percentages of absolute alcohol, by weight and volume. London: J & A Churchill, ASIN B0008B5HOU.