Q698: If I go out drinking on a night, what are the possible effects on my driving the next day?
There is no definitive answer as to when you would be under the legal limit as it depends on a lot of factors. Your body size and other factors in your genetic makeup affect this sort of rule.
As a very rough guide for a healthy adult, ignoring the first hour you should deduct an hour for each unit of alcohol you consume. A unit is half a pint of normal strength lager/beer, a single measure of spirits or a standard glass of wine.
This is not a rule that should be relied upon but a warning as to how long alcohol can linger in your system and the possible consequences of driving the following day.
If you eat a meal whilst consuming alcohol this does help to soak up the alcohol and release it at a much slower rate (but eating much later after an evening of heavy drinking does not generally help).
However, lack of sleep and feeling unwell can affect your driving and there are other offences that you could commit if you drive after a heavy night out even if you are not over the limit.
You can purchase breathalysers but we cannot recommend any brand or comment on how reliable they are.
If you are stopped the day after and are over the limit, you are classed as a drink driver and will face the same penalties. Ignorance of the alcohol level in your system is no defence.