What is an alcohol unit?
One unit is 10ml or 8g of pure alcohol. Because alcoholic drinks come in different strengths and sizes, units are a way to tell how strong your drink is.
It takes an average adult around an hour to process one unit of alcohol so that there’s none left in their bloodstream, although this varies from person to person.
As an approximate guide one unit of alcohol is contained in:
- A half-pint of normal strength (abv 4% vol.) beer, lager or cider;
- A small (125 ml) glass of wine with an abv of 8%;
- A single shot (25 ml) of spirits; and
- An ordinary measure (50 ml) of sherry, port or vermouth with an abv of 20% vol.
Calculating Units
To calculate the number of units of alcohol you will need to use the following formula.
Volume of drink (in millilitres) x abv (% volume alcohol) ÷ 1000 = number of units of alcohol.
Alcohol by volume
Alcohol content is also expressed as a percentage of the whole drink. Look on a bottle of wine or a can of lager and you’ll see either a percentage, followed by the abbreviation ‘ABV’ (alcohol by volume), or sometimes just the word ‘vol’. Wine that says ‘13 ABV’ on its label contains 13% pure alcohol.
