In the UK 1 unit of alcohol is equal to 10 ml of pure alcohol, which equates to 8 g of alcohol.

Therefore, if a patient drinks one 500 ml can of 6% strength cider, they have consumed 3 units of alcohol (0.06 x 500 ml = 30 ml of pure alcohol = 3 units of alcohol).

Some examples of units in common drinks are:

* 750 ml of 37.5% strength vodka or other spirit: 28 units

* 750 ml of 12% strength wine: 9 units

* 1 pint (568 ml) of 4% strength beer: 2.3 units

* 1 pint (568 ml) of 5% strength beer: 2.8 units

* 175 ml (1 glass) of 13% strength wine: 2.3 units

* 250 ml (1 large glass) of 13% strength wine: 3.25 units

* 1 litre of 7.5% strength cider: 7.5 units.