What are "standard drinks"?
The concept of a "standard drink" or "unit" is a useful tool for information and advice about drinking practices and prevention, and an important component of any comprehensive alcohol policy.
Where they exist, official definitions of standard drinks or units are generally issued by governments.
For public health purposes, standard drink definitions are often applied in conjunction with drinking guidelines for avoiding potential harm and are intended to assist consumers in monitoring their own alcohol consumption.
They are also often paired with "typical" sizes of drinks that contain the "standard" amount of ethanol.
As such, standard units have become an important component of many education efforts around alcohol consumption.
For commercial purposes, they are intended to offer guidance with regard to serving and packaging sizes.
To date, there is no common convention to define a standard drink measure across countries or in the scientific literature.
- Where serving sizes are defined, these measures depend to a great extent on local culture and customs and may vary according to the type of beverage alcohol–beer, wine, or spirits.
- Official "drinks" or "units" generally contain between 8 and 14 grams of pure ethanol.
The strength of different types of beverage alcohol varies significantly. Even within a given sector, there is considerable variation across different beverages. In addition, many drinks are mixed with so-called "soft drinks" or water.
In order to make measurement as uniform as possible, standard drink strength is normally expressed in grams of absolute ethanol.
What it means in practice is that a "standard drink" will always contain a given amount of absolute ethanol, regardless of whether it is beer, wine, or distilled spirits.
International government definitions of standard drinks or units vary significantly in size and alcohol content:
|Standard drink / unit size (in grams of ethanol)
||Australia, France, Hungary, Ireland, New Zealand, Poland, Spain|
||Denmark, Italy, South Africa|
||Portugal, United States|
|Last updated in May 2009|
(See Policy Table. International Drinking Guidelines)
Different researchers may also use different definitions of standard drinks. Standards currently used in research can range from 8 to 28 grams, making comparisons across studies difficult.
Moreover, much of the beverage alcohol consumed is drunk in noncommercial settings, such as private homes or other venues where sizes of glasses or amounts served may vary.
In the case of noncommercial alcohol, the strength of a beverage may not be known; consumption may take place from communal drinking vessels, making it hard to estimate how much alcohol is consumed.