Unit of alcohol
![A large (250 ml) glass of 12% ABV red wine has about three units of alcohol. A medium (175 ml) glass has about two units.[Note 1]](/uploads/202502/18/Red_Wine_Glass3609.jpg)


Units of alcohol 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.