The Catholic University of America

Blood Alcohol Content (BAC)

What's in a Drink?

It is important to define what “a drink” means. Normally, a drink is thought of as:

  • One beer
  • One mixed drink
  • One glass of wine
  • One shot of alcohol

But it is important to understand the formal definition is actually:

  • 12 ounces of beer
  • 4-5 ounces glass of wine (12-15% alcohol by volume)
  • 1.5 ounces of 80-proof (40% alcohol) distilled spirits

Each of these contains the same amount of pure ethanol, about 0.6 ounces. In other words, a 20-ounce mug of beer is considered more than a drink—it is actually closer to a drink and a half. If a person orders a mixed drink at a bar or at a party, it may be possible that whoever mixed the drink may have put in more than 1.5 ounces of alcohol.

The size and content of the drink, as well as the number of drinks consumed, all influence the amount of alcohol in a person’s blood, which is measured as the BAC, or Blood Alcohol Concentration.

Blood Alcohol Concentration (BAC) Levels

.01–.07 Feeling is mildly relaxed, a little lightheaded. Inhibitions are loosened, feeling less cautious. Judgment abilities are slightly impaired. No real feeling of the depressant effects of alcohol have occurred yet. Behavior may become exaggerated and emotions intensified.

.08–.13 Motor skills are starting to become impaired and sense of balance may be compromised. Emotions become a bit exaggerated perhaps loud or aggressive. It is dangerous (and illegal) to drive. Judgment is impaired, and there may be difficulty evaluating sexual situations. One may believe they are functioning better than they actually are.

.14–.19 The “good feelings” of euphoria begin to give way to some negative feelings such as anxiety and restlessness. Feelings of tiredness may begin as the depressant qualities of alcohol begin to take effect. There will be trouble walking or standing and a great increase in the risk of physical injury. Feelings of nausea may occur. Men may have difficulty achieving or maintaining an erection.

.20–.24 Confusion and disorientation occurs. Nausea is likely experienced. The gag reflex is impaired, increasing the risk of choking on vomit. Standing can be very difficult. Injury may be caused to the body without realization, as pain may not be felt. Blackouts are likely.

.25–.29 Almost all aspects of brain function are severely impaired. Passing out may have occurred by this point. Vomiting is likely and the chance of asphyxiation on vomit is greatly increased. If still conscious, the risk of personal injury is high because there is little to no physical control. Emotions are numb.

.30–.34 If still awake, the level of consciousness is that of a stupor, with little or no comprehension of location and what is going on. There have been numerous cases of alcohol poisoning and death in this range of BAC. The need for medical help is eminent.

.35 & UP This is the level of surgical anesthesia. Coma is possible. The lungs and heart rate are slowing to the point of stopping. Seek immediate medical help.

Adapted from The BACCHUS Network bacchusnetwork.org