What Is Blood Alcohol Content (BAC)?

When you drink alcohol, a molecule known as ethyl alcohol or ethanol, the substance is absorbed from your digestive system into your blood and then transported around your body and into your brain.

Blood ethanol levels are measured in BAC, which stands for either blood alcohol content or blood alcohol concentration.

Key Blood Alcohol Levels

The more you drink the more your BAC will rise, along with the degree of impairment you will likely experience.

Key blood alcohol levels and the effects of alcohol intoxication at each include:

0.01 – 0.03%

After your first drink is absorbed, you may feel some mild warmth or relaxation.

0.04 – 0.06%

Behavior begins to change, often with increasing talkativeness, volume, and extraversion. Inhibition is reduced and you may notice some changes to muscle control and reaction speed.

0.07 – 0.09%

In the United States, it’s illegal to drive at or above .08% BAC. At this stage, alcohol has noticeable impacts on judgment, reaction time, alertness, and visual clarity.

0.10 – 0.14%

Obvious signs of alcohol intoxication, including slurred speech, blurred vision, drowsiness, aggression or other mood changes, loss of balance and coordination, and dysphoria with feelings of restlessness or anxiousness.

0.15 – 0.19%

At twice the legal limit for driving and beyond you may have difficulty walking and accidents become more common. Speech, memory, decision-making, and wakefulness will be compromised, and dysphoria may become even more severe.

0.20 – 0.29%

Disorientation, confusion, and loss of physical control over one’s body. Feelings of pain will likely be numbed and stupor, nausea, vomiting, loss of bladder control, and blackouts (a form of amnesia or short-term memory loss) are likely.

Vomiting at this stage can be dangerous or deadly if the gag reflex has been impaired.

0.30 – 0.39% & Above

When BAC levels increase over .30 the potential for death and other severe effects relating to alcohol poisoning increase dramatically. Breathing, heart rate, and body temperature may all drop to critical levels and medical intervention is advisable.

BAC & A Standard Drink

A standard drink is defined as:

  • 12 oz. regular beer (4.5% alcohol)
  • 8 oz. malt liquor (7% alcohol)
  • 5 oz. glass of wine (12% alcohol)
  • 1.5 oz. shot of hard liquor (40% alcohol)

As a rule of thumb, expect a single standard drink to raise your BAC by approximately .02% for a period of about an hour.

DUIs & Measuring Blood Alcohol Content

Driving under the influence is a crime that carries various penalties, potentially including jail time, in different states and counties.

BAC levels may be measured in two different ways:

Breathalyzer Tests

Police officers may use a breathalyzer test on drivers when they suspect drunk driving. The breathalyzer device measures the amount of alcohol on an individual’s breath, delivering an instant, if somewhat imprecise, result.

Blood Alcohol Tests

For this test, blood samples are taken from a vein on your arm and put through a gas chromatograph, which measures the precise content of the blood, including ethanol. Results of blood alcohol tests are highly accurate for between six and twelve hours after your last drink.

Factors Influencing Blood Alcohol Content

If two people have the same number of drinks over the same period of time, they may still have very different BACs and degrees of impairment due to:

  • body weight: larger individuals can generally drink more with less change to their BAC
  • gender: men tend to be both larger and better able to metabolize alcohol than women
  • metabolism: some individuals lack the enzymes necessary to process alcohol effectively, while others are able to metabolize it more quickly than average
  • tolerance: those who drink often may better tolerate the effects of alcohol, even if their BAC is similar to someone with a much higher degree of impairment
  • other medications or drugs: many drugs interact with alcohol in unpredictable ways, potentially increasing impairment and the effects of alcohol consumption
  • rate of consumption: drinking fast or binge drinking increases the effects and risks of alcohol versus drinking the same amount more slowly
  • last meal: drinking on an empty stomach increases the rate at which alcohol is absorbed, which also increases the risk of severe impairment

Help For Alcohol Use Disorder

Northeast Addictions Treatment Center provides the very best continuum of care, not only for adults who struggle with alcohol abuse but for their families as well.

If you have an unhealthy relationship with alcohol, consider reaching out to our professional staff today and let us help you begin a new chapter today.

Written by
Northeast Addition Editorial Team

©2023 Northeast Addition Center | All Rights Reserved

This page does not provide medical advice.

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