For alcohol to leave your blood and get out of your system fully it takes around 1 hour per every ounce of alcohol that you consume.
So if you consume 12 ounces of alcohol then it would take 12 hours for the alcohol to get out of your blood.
If you drink 24 ounces of alcohol then it will take 24 hours for the alcohol to leave your system and if you drink 48 ounces of alcohol then it takes 48 hours for the alcohol to leave your blood.
But if you do drink alcohol as in more than a couple of beers then wait at least a day or so before driving to allow the alcohol to fully leave your system.
The same with other alcohol as well such as whisky, wine etc.
Make sure to allow enough time for the alcohol to leave your blood and system before driving if you drink more than the legal limit for driving.