How many alcohol units does the standard legal drink driving limit equal to?
OK, so one UK unit is 10ml of alcohol. This is exactly one normal pub measure of 25ml (not 35 and someone else said) 40% spirit. It is often claimed to be a small glass of wine, or half a pint of beer, but in fact most wines and beers currently have far higher alcohol, and wine is typically served in oversized glasses. 10ml alcohol is about 8g (its lighter than water). If you are asking what is a safe amount to be within the law, then the answer is that it is too variable depending on metabolism, body size and weight, diet, and other factors. So just dont drink and drive at all. If you are looking for a calculated theoretical limit, there is about 5 litres of blood in a body, or 50 times 100ml. The total disolved alcohol would have to be 50 * 80mg or approx 4g. So in theory half a shot would be enough to fail a blood test. Reality is rather different, but it should be clear from this that even small amounts of alcohol could risk breaking the limit.
It varies by weight. An average size person could have one or two pints and still feel fine but not pass the test. While a person of larger size with two pints would pass the test. It all has to do with biology. Your body processes alcohol at a set rate, about 500ml of beer will take one hour to clear out your blood stream. You may be able to handle three or four pints and still have a level of decorum suitable for a social situation. However, you may be double the legal limit to drive. Good rule of thumb, wait one hour per drink taken to drive. Or just take a taxi (or walk) to the pub.
