Alcohol units are used in the United Kingdom (UK) as a measure to quantify the actual alcoholic content within a given volume of an alcoholic beverage, in order to provide guidance on total alcohol consumption.
A number of other countries (including Australia, Canada, New Zealand, and the US) use the concept of a standard drink, the definition of which varies from country to country, for the same purpose. Standard drinks were referred to in the first UK guidelines (1984) that published "safe limits" for drinking, but these were replaced by references to "alcohol units" in the 1987 guidelines and the latter term has been used in all subsequent UK guidance.
Containers of alcoholic beverages sold directly to UK consumers are normally labelled to indicate the number of units of alcohol in a typical serving of the beverage (optional) and in the full container (can or bottle), as well as information about responsible drinking.
As an approximate guideline, a typical healthy adult can metabolise (break down) about one unit of alcohol per hour, although this may vary depending on sex, age, weight, health, and many other factors.