One alcohol unit is measured as 10ml of pure alcohol. Thisequals one 25ml single measure of ****** (ABV 40%), or a third of apint of **** (ABV 5-6%) or half a standard (175ml) glass of redwine (ABV 12%)The average human liver process approximately 1 unit of alcoholper hour. This means that if you drink 12 units, it'll take youroughly 12 hours to fully sober up.For your "tall boy", you need to work out how many units are inyour cans (beers in cans come in different strengths), this will bewritten on the outside of the can.Realistically you should wait until you have metabolised ALL thealcohol before you drive.