Calculating the amount of alcohol in a drink
The alcohol content of drinks can vary enormously. It depends on the type, size and strength of the drink.
Units are the official measurement of alcoholic beverages in the UK. A 'unit' is equivalent to 8 grams of pure alcohol. But the alcohol volume in products varies a lot. It's not as simple as one drink = one unit. Some strong beers contain nearly 3 units per pint rather than the 2 units found in ordinary strength lager. The measures may vary too (a 'double' vodka will have double the units), while a large glass of wine (175ml) can be over 2 units.
1 unit = half a pint of ordinary strength lager, beer or cider (284ml at 3.5% ABV)
1.5 units =330ml bottle of beer, lager or cider (4 or 5% ABV)
3.5 to 4 units = 440ml can of strong beer, lager or cider (8 or 9% ABV)
1.5 units = a small glass of wine (125ml at 12% ABV)
1 unit = a single measure of spirit (25ml at 40% ABV) or 10ml of pure alcohol
1.4 units = 'ready to drink' spirit-based drink (275ml at 5% ABV)
The number of units in a drink can be calculated using this formula (*ABV = alcohol by volume), or by using the 'unit calculator' at http://www.drinkaware.co.uk/howmany.php:
volume of glass/bottle (ml) x ABV* (%)