Alcohol by volume
Encyclopedia
Alcohol by volume 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.
In some countries, alcohol by volume is referred to as degrees Gay-Lussac (after the French chemist Joseph Louis Gay-Lussac
).
, which in the United States is twice the alcohol-by-volume number, while in the United Kingdom it was 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 However, since 1980, alcoholic proof in the UK has been replaced by abv as a measure of alcohol content.
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.
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.
:
Where 1.05 is number of grams of ethanol produced for every gram of CO2 produced and .79 is the density of ethanol alcohol,
However, many brewers use the following formula:
Ethanol
Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...
) is contained in an alcoholic beverage
Alcoholic beverage
An alcoholic beverage is a drink containing ethanol, commonly known as alcohol. Alcoholic beverages are divided into three general classes: beers, wines, and spirits. They are legally consumed in most countries, and over 100 countries have laws regulating their production, sale, and consumption...
(expressed as a percentage of total volume).
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
Joseph Louis Gay-Lussac
- External links :* from the American Chemical Society* from the Encyclopædia Britannica, 10th Edition * , Paris...
).
Typical levels
Details about typical amounts of alcohol contained in various beverages can be found in the articles about individual drinks.Alcohol proof
Another way of specifying the amount of alcohol is alcohol proofProof (alcohol)
Alcohol proof is a measure of how much alcohol is contained in an alcoholic beverage. The term was originally used in the United Kingdom and was defined as 7/4 times the alcohol by volume . The UK now uses the abv standard instead of alcohol proof. In the United States, alcoholic proof is defined...
, which in the United States is twice the alcohol-by-volume number, while in the United Kingdom it was 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
Miscibility
Miscibility is the property of liquids to mix in all proportions, forming a homogeneous solution. In principle, the term applies also to other phases , but the main focus is usually on the solubility of one liquid in another...
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, yeastYeast
Yeasts are eukaryotic micro-organisms classified in the kingdom Fungi, with 1,500 species currently described estimated to be only 1% of all fungal species. Most reproduce asexually by mitosis, and many do so by an asymmetric division process called budding...
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
Hydrometer
A hydrometer is an instrument used to measure the specific gravity of liquids; that is, the ratio of the density of the liquid to the density of water....
is used to measure the change in specific gravity
Specific gravity
Specific gravity is the ratio of the density of a substance to the density of a reference substance. Apparent specific gravity is the ratio of the weight of a volume of the substance to the weight of an equal volume of the reference substance. The reference substance is nearly always water for...
(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. BerryCyril Berry
Cyril J J Berry , widely cited as CJJ Berry, is best known as the author of the popular book First Steps in Winemaking, which has sold more than three million copies worldwide....
:
Beer
The calculation for beer is:Where 1.05 is number of grams of ethanol produced for every gram of CO2 produced and .79 is the density of ethanol alcohol,
- ABV = ((1.05 * (Starting SG – Final SG)) / Final SG) / 0.79 * 100
However, many brewers use the following formula:
- ABV = (Starting SG - Final SG) * 131