It obviously depends upon how much you’ve had to drink. In general, though, alcohol is burned from your system at about 0.15 grams per hour.
For example, if you’ve had just one drink, your blood alcohol content (BAC) would be about 0.02. After about an hour, the BAC would be nearly zero. If you had a BAC of 0.2, though, it would take nearly 13 hours to reach a zero level.