A Guide to Understanding Blood Alcohol Content

By Kayla Loibl | Last Edited: November 12, 2020 | 4 Sources

What is BAC?
How to Calculate Your BAC

Factors That Contribute to Your Blood Alcohol Content

Blood Alcohol Content, or BAC, is how we measure the amount of alcohol in a person. It refers to alcohol (ethyl alcohol or ethanol) percentage in an individual’s blood stream. A BAC equals to .10% indicates that an individual's blood supply has one part alcohol per 1000 parts blood.

In its most basic form, calculating an individual’s BAC level depends on how much alcohol was processed in a person’s body over a period of time. 

There are several factors that contribute to your BAC which we will get into.  Alcohol facts may be a good page to read to gain a refresher into some questions regarding drinking.

We live in an age of technology, which can be used to our advantage for this. Drunk Calc is a free resource that can offer you an estimate for what your BAC is after drinking. Other ways to figure out your blood alcohol content include using a breathalyzer or having blood work done.

It is important to note that this calculator, and others like it, are an estimate based on information provided and may not be 100% accurate. For this reason, they should not be used as a tool when deciding behaviors such as driving or operating other machinery while intoxicated.

What Implications are There for Different BAC Levels?

You used a calculator, and are curious where you fall in the continuum of impairment. Again, keep in mind that this may not be true for everyone, as factors such as tolerance, can make a difference in how you physically feel despite having a higher blood alcohol content.

Blood Alcohol Content Expected Effects of the Alcohol
0.02% to 0.04% Feeling relaxed, maybe lightheaded, feeling warm, some slight motor impairment
0.05% to 0.07% Feeling buzzed, lower inhibitions, slight impairment with reasoning and memory, exaggerated emotions both positive and negative
0.08% to 0.10% Legally impaired, euphoria, fatigue, impaired balance, speech, vision, reaction time and hearing, judgement and self-control are also impaired
0.11% to 0.15% Drunk, may begin to feel depressive effects of alcohol such as anxiety and depression, motor impairment, judgement is impaired, perception in severely impaired
0.16% to 0.19% Very drunk, nausea, feeling a stronger sense of depression, disorientation, dizziness, blurred vision, even further judgement impairment
0.20% to 0.24% Dazed and confused, significant disorientation to place and time, increased nausea and vomiting, may need assistance walking, blacking out is likely
0.25% to 0.30% Stupor, all mental and physical functioning are significantly impaired, increased chance of accidents and getting hurt, may pass out from drinking, inability to comprehend conversations
0.31% and higher Coma, this is equivalent to a surgical level of amnesia, at risk for acute alcohol poisoning, risk of death due to respiratory arrest is likely in half of drinkers

Suffice it to say, the higher your Blood Alcohol Count, the more impaired you become because of the alcohol’s effects. Depending on where you live, there may be different laws regulating what legally impaired is. Due to this, be mindful of your intoxication level before doing things such as driving and operating machinery.

Another factor to consider is that some locations, such as New York State, have laws that increase the severity of an individual who drives impaired with any children in the car. Not only would you be charged with the typical DWI, there would be additional legal charges to address that concern.

Some workplaces, specifically safety sensitive jobs, have a zero tolerance rule for a level of intoxication tolerated at work. Depending on how much alcohol is consumed the day before, an individual may wake up with a residual BAC. This is not uncommon among alcoholics and heavy drinkers. The danger comes when you don’t feel impaired, yet register with an elevated blood alcohol content.

Let’s clarify how having a higher tolerance to alcohol effects your blood alcohol content. Tolerance simply means that you need to consume a higher amount of alcohol to have similar effects as you did previously.

Blood alcohol content refers to the amount of alcohol in you, which would make these two separate things. With a higher tolerance to alcohol, you are likely to have a higher BAC without the sense of impairment that someone who does not have a tolerance have.


What is the Recommendation for Drinking Alcohol?

If you are reading this and are aware that you have an addiction to alcohol and or other addictive substances, the answer is simple. The recommendation would be for you to stay sober and not drink.

The majority of the medical and mental health field view alcohol addiction as a chronic and progressive disease. This means that it is highly unlikely that a person who is a recovering alcoholic would be able to return to “normal” or non-addictive drinking behaviors.

If you are reading this and you do not identify with the previous two paragraphs, then we have a different answer. According to the National Institute on Alcohol Abuse and Alcoholism,

  • “moderate drinking is up to 1 drink per day for women 
  •  up to 2 drinks per day for men”. 

When considering what 1 drink is, please revert back to the information provided regarding 1 standard drink size.

The National Institute on Alcohol Abuse and Alcoholism defines binge drinking as follows:

· “NIAAA defines binge drinking as a pattern of drinking that brings blood alcohol concentration (BAC) levels to 0.08 g/dL. This typically occurs after 4 drinks for women and 5 drinks for men—in about 2 hours.

· The Substance Abuse and Mental Health Services Administration (SAMHSA), which conducts the annual National Survey on Drug Use and Health (NSDUH), defines binge drinking as 5 or more alcoholic drinks for males or 4 or more alcoholic drinks for females on the same occasion (i.e., at the same time or within a couple of hours of each other) on at least 1 day in the past month.”

Similarly, the definition for heavy alcohol use is more than 4 drinks on any day for men, and more than 3 drinks in one day for women. If you met the criteria for heavy drinking five days in the past month, then you would also fit criteria for a binge drinker.

What Can I Do If I am Worried About My Drinking?

If you are reading because you are concerned about your drinking behaviors, know that you are not alone. There are many options for help and depend on what your drinking behaviors look like.

For someone who feels as though they may drink too much, and do not meet criteria for an addiction, individual therapy may be a good option.

You may not be an alcoholic at this time, however if you continue heavily drinking, chances are you could end up developing an addiction to alcohol. Individual therapy can help you figure out why you’re drinking so much, and if there is healthier changes that can be made to address your initial concern.

If you feel that you have a significant problem, it may be a wise and needed choice to go to an alcohol detoxification program. Alcohol withdrawal can lead to death and is quite dangerous for your health. From here, you could do an inpatient treatment program, some individuals are able to go to an outpatient program, again depending on their drinking.

For someone who is not ready to commit to treatment or therapy, it is possible to check out recovery meetings such as Alcoholics Anonymous, Smart Recovery and other similar options.

Have an appointment with your Primary Physician and have an open discussion about your concerns. They may have an idea of what would be a good fit for you, and could further discuss health concerns that come along with heavy alcohol use. For more on signs of alcoholism, please click the link.

        Blood Alcohol Content      
 Factors Contributing 

So what factors go into how a person’s blood alcohol content is calculated? These are the things that the Drunk Calc would take into consideration:

  • How many drinks you consumed ( using standard sizing)
  •  How long it took for you to consume the alcohol
  •  Your weight
  •  Your biological sex
  •  If you are hungry

Research has shown than men and women metabolize alcohol differently due to differences in their body, specifically the enzymes that are used with the metabolizing of alcohol. Women have less alcohol dehydrogenase enzymes to process and break down alcohol in their stomach. Individuals who weigh more, tend to have a lower blood alcohol content when compared to someone who weighs less that has consumed the same alcohol in the same amount of time.

It is important to be mindful of the criteria for one standard drink. Standard drinks may not be what you pour for yourself or what is served to you. Drink measurements are as follows:

  •  One 12 oz. regular beer (4.5% alcohol)
  •  One 7 oz. malt liquor (7% alcohol)
  •  One 5 oz. glass of wine ( 12% alcohol)
  •  One 1.5 oz. shot of hard liquor (40% alcohol)
  •  One-third jigger(.5 oz.) of Everclear (95% alcohol)

One thing to note when calculating the standard drink size, be mindful of the percentage of alcohol. For example, craft beers can have varying alcohol content which would have an impact on a person’s blood alcohol content. Similar effects would be noted for hard liquor with more than 40% alcohol.

If you or someone close to you wants help and advice on quitting drinking then take a look at the following pages:

Lead Writer/Reviewer : Kayla Loibl

Licensed Medical Health Professional 


I am a Mental Health Counselor who is licensed in both New York (LMHC) and North Carolina (LCMHC). I have been working in the Mental Health field since 2015. I have worked in a residential setting, an outpatient program and an inpatient addictions program. I began working in Long Island, NY and then in Guelph, Ontario after moving to Canada. Read More


National Institute on Alcohol Abuse and Alcoholism. Overview of Alcohol Consumption. https://www.niaaa.nih.gov/alcohols-effects-health/overview-alcohol-consumption

Stanford Office of Alcohol Policy and Education. What Is BAC?. https://alcohol.stanford.edu/alcohol-drug-info/buzz-buzz/what-bac

College of St. Benedict St John’s University. Understanding Blood Alcohol Content (BAC). https://www.csbsju.edu/chp/health-promotion/alcohol-guide/understanding-blood-alcohol-content-(bac)

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