Blood Alcohol Concentration

What is Blood Alcohol Concentration (BAC)?

BAC refers to the percentage of alcohol in a person's bloodstream. A BAC of 0.10% means that an individual's bloodstream contains one part alcohol for every 1,000 parts blood.

Why is BAC Important?

When consumed, alcohol goes directly into the bloodstream and affects every organ of the body, including the brain. As one gets more and more intoxicated, the brain begins to shut down and adverse consequences can ensue.

What Factors Determine a Person's BAC?

There are several factors that determine one’s BAC. The main factors are gender, weight, number of standard drinks* consumed, and time in which the drinks were consumed. Other factors that play a role are one’s physical condition, what one has had to eat, how much sleep they have had and any medications they are taking.

What is a Standard Drink*?

According to the National Institute on Alcohol Abuse and Alcoholism, a standard drink is "any drink that contains about 14 grams of pure alcohol (about 0.6 fluid ounces or 1.2 tablespoons)." This equates to:

  • 12 oz. of beer
  • 8-9 oz. of malt liquor
  • 5 oz. of table wine
  • 1.5 oz. of 80-proof liquor

Alcoholic drinks often contain more than one standard drink. It is important to know how much you are drinking to keep track of your blood alcohol concentration. Here are several common drinks that are larger than one standard drink and how many standard drinks they actually contain.

  • 16 oz. beer = 1.3 standard drinks
  • 22 oz. beer = 2 standard drinks
  • 40 oz. beer = 3.3 standard drinks
  • 12 oz. malt liquor = 1.5 standard drinks
  • A 750 ml bottle of wine = 5 standard drinks
  • 12 oz. margarita = approximately 2 to 4 standard drinks
  • 12 oz. cup of "trashcan punch" = approximately 4 to 10 standard drinks
  • 1.75 L bottle of 80-proof liquor = 39 standard drinks
BAC Calculation

Since many factors play into one’s BAC level, it is very difficult to calculate. However, there are charts available to help estimate one’s BAC level based upon gender and weight.

BAC and its Effects on the Body

When alcohol enters the body, it affects all organs, including the brain. As the brain becomes more and more poisoned with alcohol, a person who drinks alcohol will experience certain effects.

  • BAC .02% - .04%: You may feel mildly relaxed and maybe a little lightheaded. Your inhibitions are slightly loosened and whatever mood you were in before you started drinking may be mildly intensified.
  • BAC .05% - .07%: You may feel warm and relaxed. If you're the shy type when you're sober, you would become more outgoing. Your behavior may become exaggerated, making you talk louder or faster or act bolder than usual. Emotions are intensified, so your good moods are better and your bad moods are worse. You also may feel a mild sense of euphoria.
  • BAC .08% - .09%: You may believe you're functioning better than you actually are. At this level, you may start to slur your speech. Your sense of balance is probably off, and your motor skills are starting to become impaired. Your ability to see and hear clearly is diminished. Your judgment is being affected, so it's difficult for you to decide whether or not to continue drinking. Your ability to evaluate sexual situations is impaired. People may jokingly refer to this state of mind as "beer goggles," but this blood alcohol concentration can have serious repercussions.
  • BAC .10% - .12%: At this level you may feel euphoric, but you lack coordination and balance. Your motor skills are markedly impaired, as are your judgment and memory. You probably don't remember how many drinks you've had. Emotions are exaggerated, and some people become loud, aggressive or belligerent. Men may have trouble getting an erection when their blood alcohol concentration is this high.
  • BAC .14% - .17%: Your euphoric feelings may give way to unpleasant feelings. You have difficulty talking, walking or even standing up. Your judgment and perception are severely impaired. You may become more aggressive and are at increased risk of accidentally injuring yourself or others. This is the point when you may experience a blackout.
  • BAC .20%: You may feel confused, dazed or otherwise disoriented. You need help to stand up or walk. If you hurt yourself at this point, you probably won't realize it because you won't feel pain. Even if you are aware that you've injured yourself, you probably won't do anything about it. At this point you may experience nausea and start vomiting. Your gag reflex is impaired, so you could choke if you throw up. Since blackouts are likely at this level, you may not remember any of this.
  • BAC .25%: All mental, physical and sensory functions are severely impaired. You're emotionally numb. There's an increased risk of asphyxiation from choking on vomit and of seriously injuring yourself by falling or other accidents.
  • BAC .30%: You're probably in a stupor. You have little comprehension of where you are or what's really going on around you. You may suddenly pass out and be difficult to awaken.
  • BAC .35%: This blood alcohol concentration is similar to the physical effects of surgical anesthesia. You may stop breathing.
  • BAC .40% - .50%: You are probably in a coma. The nerve centers controlling your heartbeat and respiration are slowing down and it's a miracle if you survive.