Standard drink


A standard drink is a measure of alcohol consumption representing a hypothetical beverage which contains a fixed amount of pure alcohol. A standard drink varies in volume depending on the alcohol concentration of the beverage, but it always contains the same amount of alcohol and therefore produces the same amount of drunkenness.
The standard drink is used in relation to recommendations about alcohol consumption and its relative risks to health. Many government health guidelines specify low to high risk amounts in units of grams of pure alcohol per day, week, or single occasion. The concept of the standard drink is meant to help visualize and estimate the absolute alcohol content of various drink concentrations and serving sizes.
For example, in the United States, a standard drink contains about 14 grams of alcohol. This corresponds to a glass of 4.1% beer, a glass of 12% ABV wine, or a so-called "shot" of spirit, assuming that beer is 5% ABV, wine is 12% ABV, and spirits is 40% ABV. Most wine today is higher than 12% ABV. 80 proof is still the standard for spirits, though higher alcohol content is common.
Different countries define standard drinks differently. For example, in Australia, a standard drink contains 10 grams of alcohol, but in Japan, one "unit" contains approximately 20 grams. In addition, a standard drink is often different from normal serving size in the country in which it is served.
Labeling is usually required to give an indication of alcoholic content of a serving. Australia requires that "the label on a package of an alcoholic beverage must include a statement of the number of standard drinks in the package".
The term "standard drink" was used in the United Kingdom in the first guidelines that published "safe limits" for drinking, but this was replaced by reference to units of alcohol in the 1987 guidelines and that term has been used in all subsequent UK guidance. A unit of alcohol is defined there as 10 millilitres of pure alcohol. This definition is independent of the strength and amount of any individual alcoholic beverage. The number of units of alcohol in a bottle or can are indicated on the drink container. Typical servings deliver 1–3 units of alcohol.

Definitions in various countries

These are the amounts of alcohol defined by several countries for standardising measurement of drinking levels and providing public health information. As well as choosing different quantities for a "standard" drink, some choose to base the definition on mass of alcohol while others base the unit on the volume. For comparison, both measurements are shown here. There is no single standard, but a standard drink of 10g alcohol, which is used in the WHO AUDIT 's questionnaire form example, have been adopted by more countries than any other amount. The terminology for the unit also varies, as shown in the Notes column.
CountryMass Volume Notes
Australia1012.7
Austria2025.3
Canada13.617.2
Denmark1215.2
Finland1215.2
France1012.7
Germany1113.8standardglas defined as containing 10 - 12g
Hong Kong1012.7
Hungary1721.5
Iceland810áfengiseining defined as 8g but treated as equivalent to 10mL
Ireland1012.7
Italy1012.7unita standard defined as 10mL
Japan19.7525"unit ". MHLW's conventional unit, based on 1 gō of sake. Not any "standard".
Japan1012.7"drink ". Introduced around 2011CE to align with the WHO AUDIT, and to avoid the conventional unit of giving a false impression of "minimum amount to drink". Sometimes also called "unit ". Has no implication of being any "standard".
Netherlands1012.7
New Zealand1012.7
Poland1012.7
Portugal1113.810 - 12g
Spain1012.7
Sweden1215.2standardglas corresponds to 33 cl 5 % beer, 13 cl wine, or a drink or shot based on 4 cl 40 % liquor
Switzerland1215.2
United Kingdom810unit of alcohol defined as 10mL but treated as equivalent to 8g
United States1417.7standard drink defined as 0.6 fl oz or 14g

Calculation of pure alcohol mass in a serving

Pure alcohol mass in a serving can be calculated if concentration, density and volume are known.
For example, a 350 ml glass of beer with an ABV of 5.5% contains 19.25 ml of pure alcohol, which has a density of 789.24 g/L, and therefore a mass of 15.19 grams.
When drink size is in fluid ounces, the following conversions can be used:
CountryVolume of fl. oz. Mass of fl. oz. of alcohol
UK28.4122.42
US29.5723.34

One should bear in mind that a pint in the UK is 20 imperial fluid ounces, whereas a pint in the US is 16 US fluid ounces. However, as 1 imperial fl. oz. ≈ 0.961 US fl. oz., this means 1 imperial pint ≈ 1.201 US pints instead of 1.25 US pints.

Time to metabolise

As a rough guide, it takes about one hour for the body to metabolise one UK unit of alcohol, 10 ml. However, this can vary with body weight, sex, age, personal metabolic rate, recent food intake, the type and strength of the alcohol, and medications taken. Alcohol may be metabolised more slowly if liver function is impaired.
To determine time to metabolise, multiply one hour by the number of alcohol units in the local definition of a standard drink. For example, in the United States one standard drink contains 14 grams ≈ 1.75 units of alcohol, and so takes the body about an hour and three-quarters to process.