October 17, 2022

What is Blood Alcohol Concentration?


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Blood alcohol concentration (BAC), also known as blood alcohol level, expresses the amount of alcohol in the blood.

The chemical name for alcohol is ethanol or ethyl alcohol. This intoxicating ingredient is found in: 

  • Beer
  • Wine
  • Distilled spirits

When you consume an alcoholic beverage, your small intestines and stomach absorb most of the alcohol. From here, alcohol enters your bloodstream. Since alcohol is a toxin, your liver metabolizes alcohol so it is filtered out of your blood.

If you consume alcohol more rapidly than your liver is able to process the substance, blood alcohol concentration increases. When this occurs, you might start feeling the effects of intoxication, informally known as drunkenness.

The liver is capable of processing one standard drink per hour. According to NIAAA (National Institute on Alcohol Abuse and Alcoholism), a standard drink is:

  • 12oz beer (5% alcohol content)
  • 5oz wine (12% alcohol content)
  • 1.5oz distilled spirits (40% alcohol content)

Blood alcohol levels are influenced by many situational and physical variables, including:

  • Weight
  • Body fat percentage
  • Digestion
  • Hydration
  • Body chemistry
  • Alcohol content of beverages consumed
  • Spacing of drinks
  • Time since last alcoholic drink
  • Prescription medications
  • Illicit drugs

All of the above factors can impact BAC levels and also the extent of impairment caused by alcohol.


This is how different blood alcohol concentration levels can affect your body and mind:


There is no alcohol in your blood and you are sober.

BAC LEVEL: 0.02%

You will start to feel relaxed with some reduction in judgment and multitasking abilities. 

Alcohol at this level starts to exert some mood-altering effects, too.

BAC LEVEL: 0.05%

Alertness levels reduce at this BAC level. Your judgment will be further impaired and you will feel less inhibited.

At this blood alcohol concentration level, you will find it harder to track moving objects, making it dangerous to drive.

Response times will decrease when your BAC level reaches 0.05%.

BAC LEVEL: 0.08%

You will lose muscle coordination and balance at these BAC levels. 

Driving at these BAC levels is dangerous as you will have difficulty regulating speed and you will struggle to react quickly enough to emergency situations.

Judgment and reasoning are both impaired. You are at increased risk of injuries.

BAC LEVEL: 0.10%

Reaction times are impaired, your thinking and speech are slurred.

BAC LEVEL: 0.15%

Altered mood, loss of balance, nausea, and vomiting are commonplace reactions to BAC levels of 0.15%.

BAC LEVEL: 0.15% TO 0.30%

The most common physical effects at these BAC levels are:

  • Drowsiness
  • Confusion
  • Vomiting


After 0.3% BAC, alcohol will have such a high concentration in your blood that it can cause deadly consequences and lead to life-threatening problems. Lethal blood alcohol concentration levels are not something to take lightly, learn more about these below and get a better idea of what you can do to help someone who is struggling.

BAC LEVEL: 0.30% TO 0.40%

This range of blood alcohol concentration is liable to trigger alcohol poisoning, also known as alcohol overdose. This can bring about a loss of conscious and can be life-threatening.


BAC levels over 0.4% are potentially lethal, potentially involving:

  • Respiratory arrest
  • Coma
  • Death

If you are drinking and believe that someone you’re with may be at deadly blood alcohol levels, contact emergency services immediately and get help. Ignoring this can lead to disastrous consequences.

Moreover, if someone who is dealing with dangerous high levels of BAC, it can be a strong sign that they are an alcoholic or have alcoholic tendencies. Reach out to an addiction treatment program, like Gratitude Lodge and get the help you need today.


Alcohol has a half-life of between four and five hours. After this point, you will have no alcohol in your system.

The following tests can detect alcohol in your system:

  • Blood test: 12 hours
  • Breath test: 24 hours
  • Urine test: 12 hours
  • Saliva test: 48 hours
  • Hair test: 90 days


If you want to address any abusive patterns of alcohol consumption or addiction in the form of alcohol use disorder, we can help you at Gratitude Lodge.

We have affordable luxury treatment centers located in San Diego, Newport Beach, and Long Beach. At these inclusive and pet-friendly rehabs, you can access the following services:

  • Medical detox: Streamline the intensity of alcohol cravings and withdrawal symptoms at our licensed medical detox centers.
  • Inpatient rehab: 30-day treatment program for alcohol use disorder.
  • IOP: If you require a more cost-effective and flexible approach to recovery from alcoholism, consider our intensive outpatient program.

After a week or so of alcohol detox, you can engage with ongoing treatment at an appropriate level of intensity. MAT (medication-assisted treatment) is proven effect for the treatment of alcoholism. This pharmacological intervention is most effective delivered in combination with behavioral interventions. You can also access these therapies at Gratitude Lodge:

  • Psychotherapies (talk therapies like cognitive behavioral therapy)
  • Counseling (group and individual)
  • Holistic therapies
  • Family therapy
  • Daily meetings
  • 12-step immersion program

When you are ready to reclaim your life from alcohol abuse, reach out to Gratitude Lodge by calling 888-861-1658.

Blood Alcohol Concentration FAQs

A deadly BAC (Blood Alcohol Concentration) refers to an extremely high level of alcohol in the bloodstream, which can lead to life-threatening consequences. It can cause severe impairment of motor skills, decision-making, and vital functions like breathing, potentially resulting in alcohol poisoning, coma, or even death. The legal limit for driving is typically much lower than the BAC considered deadly, which is why drinking and driving can be extremely dangerous and is strongly discouraged.

A lethal BAC (Blood Alcohol Concentration) refers to an alcohol level in the bloodstream that is high enough to cause death. The exact BAC level considered lethal may vary based on individual factors, but generally, a BAC of around 0.40% or higher is considered life-threatening and can lead to fatal alcohol poisoning or severe central nervous system depression.

In the United States, having a blood alcohol content (BAC) of 0.08% or higher is legally considered impaired, and you can be arrested for suspicion of driving under the influence (DUI). However, even if your BAC is above 0.00% but below the legal limit, you can still face charges for DUI based on other evidence of impairment, such as erratic driving behavior or failing a field sobriety test.

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Joe Gilmore

Joseph Gilmore

Joseph Gilmore has been working in the addiction industry for half a decade and has been writing about addiction and substance abuse treatment during that time. He has experience working for facilities all across the country. Connect with Joe on LinkedIn.
Jenni Bussi

Jenni Russe MS, LPCC

Jenni Busse MS, LPSS is the Clinical Director at Gratitude Lodge. Jenni oversees the clinical program and the clinical team at Gratitude Lodge as a whole. Jenni has worked in treatment for almost 14 years. Her background as a licensed therapist and her passion for helping others intersected with addiction recovery when she started working primarily in detox residential treatment.

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