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What Is Blood Alcohol Concentration?

woman with glass of wine

If you have ever watched Cops or taken a drivers ed course, you probably heard BAC mentioned at some point or another.

What you may not understand is exactly what BAC means and how it comes into play. As providers of alcohol addiction treatment in Philadelphia, we want to educate the general public on the intricacies and dangers behind this term.

What Is Blood Alcohol Concentration (BAC)?

Blood alcohol concentration, or BAC, refers to the percentage of alcohol in a person’s bloodstream. A person’s blood alcohol concentration level is affected by many factors including amount of alcohol consumed, duration in which the alcohol was consumed, gender, weight, medications, food in the stomach, and alcohol tolerance.

Standard Drinks and Their Alcohol Content

While they are many factors to take into account when looking at blood alcohol concentration, the biggest is how much alcohol was consumed and in what time period. A woman is considered to be binge drinking when she consumes 4 drinks in one occasion and a heavy drinker if she consumes 8 or more standard drinks in a week. In contrast, a man qualifies as binge drinking when consuming 5 drinks in one occasion and a heavy drinker when consuming 15 drinks or more a week.1

A standard drink of alcohol includes:

  • 1 beer = 12 ounces, 5% alcohol
  • 1 glass of wine = 5 ounces, 12% alcohol
  • 1 shot of liquor (at 80 proof) = 1.5 ounces, 40% alcohol1

What Do the Different Levels of Blood Alcohol Concentration Mean?

A person’s BAC affects both their physical and mental state and can also have legal consequences. Our drug rehab in PA is here to give you the facts behind the different levels of blood alcohol concentrations and what they entail.

0.02-0.04 BAC

You may start to feel some slight effects of the alcohol at this point including feeling more upbeat and slightly relaxed.

Pennsylvania has a Zero Tolerance Law. This regulation means that anyone under 21, the legal drinking age, who is caught driving with any amount of alcohol in their system will face serious consequences. 0.01 is the exception as this could be the result of a false positive.

0.04-0.07 BAC

The alcohol’s effects will start to be apparent and mild intoxication will occur. These effects may include slightly impaired judgement, mild balance problems, blurry vision, lowered inhibitions, greater likelihood of engaging in risky behaviors, and some speech impairment.

0.08 BAC

At this point, a person is considered drunk and will experience more severe side effects from drinking such as loss of coordination, slow reaction times, poor concentration, impaired memory, and poor judgment.

At 0.08 BAC, a person is no longer allowed to drive legally in the United States. Someone who is caught doing so will get a DWI and face harsh legal penalties.

0.09-0.15 BAC

When people’s blood alcohol levels are this high, they will be visibly drunk. Reaction time and coordination will be noticeably impaired. The person will also probably start to slur their words or stumble when walking.

When people hit 0.10 BAC, they are considered legally drunk in most states and could get in trouble for public intoxication depending on the circumstances.

0.16-0.25 BAC

BACs that are this high are serious. Vomiting typically occurs in this range as your body attempts to get rid of the alcohol toxins in your body. The drunk person may also be confused and in a daze. They may be unable to support their own weight and fail to feel the effects of a serious injury. Blackouts also take place in this range.

0.26-0.34 BAC

People are at risk of choking on their own vomit at this stage and signs of alcohol poisoning may begin. The brain will start to shut down as the drunk person will neglect to respond to most stimuli.

0.35 and Higher BAC

Once you hit a 0.40 BAC, it starts to become fatal. People will often slip into a coma and die from breathing difficulties.

Although a seemingly small range, the levels of blood alcohol concentration can get deadly quickly as people drink more than they realize. Do not let this happen to you. Whether you want to find professional help to stop drinking or your loved one is looking for benzo addiction treatment in Philadelphia, our rehab center has the programs and therapies you need to overcome your substance abuse problems.

Learn more about what we have to offer and how we may be able to assist today by calling 888-280-4763.


  1. CDC – Facts Sheets – Alcohol Use and Your Health
Alyssa, Director of Digital Marketing
Alyssa, Director of Digital Marketing
Alyssa is the National Director of Digital Marketing and is responsible for a multitude of integrated campaigns and events in the behavioral health and addictions field. All articles have been written by Alyssa and medically reviewed by our Chief Medical Officer, Dr. Darrin Mangiacarne.
What Is Blood Alcohol Concentration?
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