Finding out how long alcohol can stay in your system is a common question. After all, you do not want to risk trying to drive if there is still any alcohol left in your system. Unfortunately, the answer depends on many different factors. You need to measure how much you were drinking, the proof of the alcohol, and your body size as starters. How well your kidneys and liver function also factor into how long alcohol can stay in your system. Then there is the factor of how old you are, whether you are male or female, and if you ate anything before or while drinking.
Thankfully, there is a pretty good rule to follow should drinking be a part of your regular routine. Most people will have no residual alcohol left after 2-4 hours if they were drinking a can or two of beer in that time. Anything more than that, the time goes up exponentially. The best way to be sure that there is never any alcohol in your system is to stop drinking. That way, any time you need to go out, you know it is safe to do so without putting yourself, or anyone else around you, at risk.