If you haven’t consumed any alcohol, your blood alcohol concentration is 0.00%. The legal limit for drivers is 0.08%. Mathematically, this may seem like a very small difference, but alcohol is very potent and so only a small amount of change is needed to impair someone’s ability to drive.
If you’re trying to avoid getting arrested for drunk driving, then you may wonder how long you have to wait after drinking until your BAC returns to zero. There are a lot of different factors to consider, but it’s wise to know how long this tends to take.
The rate of decline
The generally accepted rate of decline for blood alcohol concentration is 0.015% per hour. There can be some exceptions to this rule, such as someone who is very small or someone who metabolizes alcohol at a faster rate than normal, but it’s a safe rule of thumb to follow. For the vast majority of people, this is how fast your BAC is going to drop.
As you can see, this means it can often take quite a while to get back to zero. Imagine that your BAC is at 0.09%. This means that you are over the legal limit. An hour later, you will be at 0.075%, which is technically under the legal limit but could still result in a DUI.
But it’s going to take you roughly six hours to get all the way back down to zero. Most people who get up past this limit are not going to be totally sober until the following day.
If you are facing drunk driving charges, the ramifications can be severe, so you need to know about your legal options.