The alcohol content of wine and other alcoholic beverages refers to the proportion of ethanol, the main type of alcohol present. The theoretically achievable alcohol content of a wine can already be calculated from the must weight in the grapes. It results from the sugar content(fructose and glucose) in the grape must, which is converted into alcohol and carbon dioxide during fermentation. In the 19th century, the chemist Joseph Gay-Lussac (1778-1850) developed a system that expresses the alcohol content in degrees (°), which is still used in some Anglo-American countries. Today, however, it is internationally common and standardised within the EU to express alcohol content in percent by volume. The measurement is made at a temperature of 20 °Celsius.

Definitions of terms

There are four different terms for alcohol content. The main interest is in how much alcohol is actually contained in the drink. In most countries, the actual alcohol content is stated on the label:

Actual alcohol content
Pure alcohol actually contained in grape must or wine.

Potential alcohol content
The amount of alcohol that would theoretically be possible if the residual sugar were fully fermented (potential = possible, as opposed to actual). In Italy, this value is often indicated according to the existing alcohol content in the form of "14% vol+4", for example. In this specific case, this means a residual sugar of the equivalent of 4% alcohol, i.e. around 65 g (1% alcohol corresponds to 16 to 17 g sugar).

Total alcohol content
Sum of actual and potential alcohol content.

Natural alcohol content
Total alcohol content before any fortification.

Calculation

During fermentation, 10 g of sugar per litre of must produces around 0.59 to 0.60% alcohol by volume. 17 grams of sugar per litre of must correspond to around 1% alcohol by volume.8 g of alcohol per litre correspond to around 1% alcohol by volume. The conversion formula is g/l = % vol × 7.894; at 12% vol this results in 94.7 g/l. In a 0.75 litre bottle, this is ≈ 71 g of pure alcohol.

One eighth (125 ml) of wine contains approximately as many grams of alcohol as the wine has per cent by volume (at 12% vol ≈ 12 g). A simple and quick method for determining the alcohol content with approximate values is the Rebelein method. Alternatively, gas chromatography or FT-IR spectrometers provide very precise values.

1 = Potassium chromate, 2 = nitric acid, 3 = potassium iodide, 4 = sodium thiosulphate, 5 = starch

Health aspects

So how high is the alcohol level if you consume a 0.75 litre bottle of wine (three quarters or six eighths of wine) with an alcohol content of 12% by volume? This also depends on your physical condition, drinking speed, gender and other factors. For a man weighing around 85kg and drinking for two hours, these "three quarters of wine" roughly equate to 1.2 per mille gross (see formula under blood alcohol concentration). For the acceptable amount to drink, see Health.

Breath alcohol calculator

Using the Widmark's formula, the per mille value after the consumption of alcoholic beverages is calculated using the per mille calculator (click) on the basis of weight, height and sex as well as the drinks consumed.

Alcoholic drinks - alcohol levels

The alcohol strengths given are to be understood as approximate guide values. For all alcoholic drinks, there are...