To estimate how much you're drinking, use these examples. A large glass of wine(250ml) at 12% alcohol by volume(abv)=3 units; a pint of lager is approx 2.3 units; a standard glass of wine(175ml) at 12% (abv)=2.1 units; a measure of spirits at 40% (abv)=1.4 units.
Attribution: BUPA