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. One unit of alcohol (UK) is defined as 10 millilitres (8 grams) of pure alcohol. Typical drinks (i.e., typical quantities or servings of common alcoholic drinks) may contain 1–3 units of alcohol. Containers of alcoholic drinks sold directly to UK consumers are normally labelled to indicate the number of units of alcohol in a typical serving (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. Formula The number of UK units of alcohol in a drink can be determined by multiplying the volume of the drink (in millilitres) by its percentage ABV, and dividing by 1000. For example, one imperial pint (568 ml) of beer at 4% alcohol by volume (ABV) contains: The formula uses . This results in exactly one unit per percentage point per litre, of any alcoholic beverage. The formula can be simplified for everyday use by expressing the serving size in centilitres and the alcohol content literally as a percentage: Thus, a 750 ml bottle of wine at 12% ABV contains 75 cl × 12% = 9 units. Alternatively, the serving size in litres multiplied by the alcohol content as a number, the above example giving 0.75 × 12 = 9 units: Both pieces of input data are usually mentioned in this form on the bottle, so is easy to retrieve. Labelling Research in the UK has shown that including pictures of units and a statement of the drinking guidelines could help people understand the recommended limits better. UK alcohol companies pledged in March 2011