# Alcohol by volume

The alcohol by volume shown on a bottle of absinthe.

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).[1][2][3] The ABV standard is used worldwide.

In some countries, alcohol by volume is referred to as degrees Gay-Lussac (after the French chemist Joseph Louis Gay-Lussac).[4]

## Typical levels

Details about typical amounts of alcohol contained in various beverages can be found in the articles about individual drinks.

[citation needed]
 Rectified spirit 95%-96%

## 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,[7][8] 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 However, since 1980, alcoholic proof in the UK has been replaced by abv as a measure of alcohol content.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).[9] 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.

### Wine

The simplest method for wine has been described by English author C.J.J. Berry:[10]

• $ABV = (\mathrm{Starting~SG} - \mathrm{Final~SG})/7.36$

### Beer

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,

• $ABV = \frac{1.05}{0.79} \left( \frac{\mathrm{Starting~SG} - \mathrm{Final~SG}}{\mathrm{Final~SG}} \right) \times 100$ [11]

However, many brewers use the following formula:

• $ABV = 131 \left( \mathrm{Starting~SG} - \mathrm{Final~SG} \right)$

## References

1. ^ "Lafayette Brewing Co.". www.lafayettebrewingco.com. Retrieved 2012-02-04.
2. ^ "Glossary of whisky and distillation". www.celtic-whisky.com. Retrieved 2012-02-04.
3. ^ "English Ales Brewery Monterey British Brewing Glossary". www.englishalesbrewery.com. Retrieved 2012-02-04.
4. ^ "Joseph Louis Gay-Lussac (1778–1850)". chemistry.about.com. Retrieved 2008-07-05.
5. ^ Robinson, Jancis. The Oxford Companion to Wine, 3rd edition, (Oxford University Press: 2006). See alcoholic strength at p. 10.
6. ^ Robinson, Jancis. The Oxford Companion to Wine, 3rd edition, (Oxford University Press: 2006). See fortification at p. 279.
7. ^ C.J.J. Berry, 1987, First Steps in Winemaking, eighth edition, Special Interest Model Books Ltd, printed in UK
8. ^ Regan, Gary (2003). The Joy of Mixology. New York: Clarkson Potter. pp. 356–357. ISBN 0-609-60884-3.
9. ^ "Realbeer.com: Beer Break - Alcohol Content In Beer". www.realbeer.com. Archived from the original on 4 July 2008. Retrieved 2008-07-05.
10. ^ Berry, C.J.J. (1987). First Steps in Winemaking. Poole, United Kingdom: Special Interest Model Books.
11. ^ Anon, 2012, Industrial Microbiology Beer Fermentation Practical, School Of Applied Sciences, RMIT University, Melbourne

## Bibliography

• 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.