Blood Alcohol Concentration (BAC) & Blood Alcohol Levels

Updated on 06/15/2022 / Under

With the ease of access to alcohol in the modern era, many drinkers don’t know about how much they actually consume or how much it truly affects one’s behavior when intoxicated. Many states have started to lower their legal toxicity levels due to investigating and discovering the heavy effects of simply consuming one or two drinks.

Blood Alcohol Levels Explained

In general, most people aren’t informed about the urgency in addressing the need to measure blood alcohol levels, especially since a certain amount would certainly guarantee death. This guide will have Blood Alcohol Levels explained as a whole along with various discussions from legality down to limits and dangers of consuming high levels of alcohol.

What are Blood Alcohol Levels?

Blood Alcohol levels are the measurement of alcohol within a person’s system. It is commonly measured by the Blood Alcohol Concentration which refers to the percentage of alcohol that is found within one’s bloodstream or breath.

The breathalyzer is one of the methods performed commonly by authorities in order to determine if one is legally intoxicated or not though there are multiple methods used in order to determine someone’s blood alcohol level units and percentage of consumption.

It is also used during life-threatening situations where someone can have the possibility of gaining alcohol poisoning due to high levels of alcohol in their blood.

Blood alcohol concentration definition: Blood Alcohol Concentration is expressed as the weight of ethanol (in grams) in 100 milliliters of blood or 210 liters of breath.

This can be measured by breath, blood, or even urine tests. There are many indicators that would normally indicate someone being intoxicated such as feeling relaxed as in euphoria, impairment or irrational judgment, lowering of caution and the slow or complete loss of memory.

As the blood alcohol levels steadily rise, so does the effects and cautions that go along with it. Soon, someone’s vision can become extremely disorientated or one might have difficulties in hearing.

Speech patterns start to break and slur as the mind starts to slow down. Reaction time might be slow and soon enough, lack of physical control.

Each person has a different state when intoxicated and that is also a difficulty when figuring out whether someone is intoxicated enough that they need someone’s aid and even some people might have violent reactions when intoxicated which would bring danger towards their surroundings.

How is the blood alcohol level calculated?

There are many factors affecting someone’s Blood Alcohol Level such as biological features such as sex, medications, body weight, and food (to a lesser extent) but is mostly affected by the amount of alcoholic drink consumption and the time between each drink consumed. The following image represents the blood alcohol level formula.

Blood alcohol content levels formula

Under Illinois law, the level of an individual's blood alcohol concentration will lead to certain presumptions on whether someone is considered legally drunk for the purposes of driving under the influence of alcohol.

  • If your blood alcohol concentration is a .0 - .04999 then you are presumed to not be under the influence of alcohol.
  • If your blood alcohol concentration is a .5 - .07999 then there is no presumption on whether you are under the influence of alcohol and the court must look to other factors to determine if you have committed the offense of driving under the influence of alcohol.
  • If your blood alcohol concentration is a .8 or above then you are presumed to be under the influence of alcohol.

It is important to remember that if your blood alcohol concentration is .049 or below you can still be charged with driving under the influence of alcohol in Cook County.

It is also important to know that even if you are presumed to be under the influence of alcohol (a blood alcohol concentration of .08 or above) that does not mean you are guilty of driving under the influence of alcohol.

The prosecutor still needs to prove their case and there are other factors the judge must consider as well.

A normal drinking alcohol level would be one or two drinks of 12 Oz. Beer but any more than that would immediately be listed as under the influence of alcohol A person’s body weight and sex are specially calculated due to the fact that it greatly affects the alcoholic metabolism of each person.

Blood Alcohol Content Chart

There are plenty of BAC charts and calculators available. Most of these can be found on the internet and are based on basic things that determine one’s blood alcohol level through charts such as weight, sex and the quantity of the drink consumed.

They also provide small descriptions of effects when intoxicated enough. One of the few drawbacks of this method is that it makes based assumptions regarding the strength of the drinks one have consumed, generally relying on weight and sex.

Most of these charts don’t take into account someone’s metabolism, health, medication, and recent consumption of food. They’re also a bit problematic to search for once someone is already intoxicated since they have little to no control over their physical state. These Blood Alcoholic level DUI charts are only for basic use and aren’t personalized enough in order to create the most accurate measurements. Here are some examples of Blood Alcohol Content charts based on sex & weight.

Blood Alcohol Level Chart for Females

# drinks in 1 hr 100 lbs 120 lbs 140 lbs 160 lbs 180 lbs 200 lbs 220 lbs 240 lbs
1 .05 .04 .03 .03 .03 .02 .02 .02
2 .09 .08 .07 .06 .05 .05 .04 .04
3 .14 .11 .11 .09 .08 .07 .06 .06
4 .18 .15 .13 .11 .10 .09 .08 .08
5 .23 .19 .16 .14 .13 .11 .10 .09
6 .27 .23 .19 .17 .15 .14 .12 .11

Blood Alcohol Level Chart for Males

# drinks in 1 hr 100 lbs 120 lbs 140 lbs 160 lbs 180 lbs 200 lbs 220 lbs 240 lbs
1 .04 .03 .03 .02 .02 .02 .02 .02
2 .08 .06 .05 .05 .04 .04 .03 .03
3 .11 .09 .08 .07 .06 .06 .05 .05
4 .15 .12 .11 .09 .08 .08 .07 .06
5 .19 .16 .13 .12 .11 .09 .09 .08
6 .23 .19 .16 .14 .13 .11 .10 .09

For example, women who weigh between 140 – 240 pounds would have an approximate blood alcohol level percentage of .04 – .07 percent (approximately 2 drinks), which could significantly affect someone’s driving skills. Any more than that would be legally intoxicated and that person will face criminal penalties.

For men of the same weight, it would be having an average blood level percentage of .03 – .06 percent (approximately 2 drinks) to have a significant change in driving skills. A drink is approximately 12 oz. of beer and there are many blood alcohol level charts in order to accurately measure your blood alcohol level.

However, once your blood alcohol level reaches .40 percent for both sexes weighing around 90 – 140 pounds, death is possible. This is the highest limit before any indication of medical help. At this rate, most aspects of the brain begin to shut down and those around these levels begin to pass out.

What are the dangers of high BAC?

Vomiting is a common occurrence and there is a chance of choking. Even awake, people within these levels have little to no physical control and are emotionally numb. At a blood alcohol level between .250 and .399 percentage, these people are most likely in need of medical attention and are considered to be at a level that indicates alcohol poisoning and in need of immediate assistance.

Once blood alcohol levels reach more than .40 percent then there is a strong possibility of either – immediate death or falling into a coma. Immediate medical assistance is needed since the lungs and the heart are slowing down almost to the point of stopping completely.

How long does it take to lower the alcohol level?

Though the only way to lower someone’s toxicity level is to simply let them rest in a closed area and let time work its way. It is the only factor for blood alcohol levels to lower even though it might have a slow effect.

For every hour, the alcohol level after the first drink lowers by .015. So for the first hour, it lowers by .015 then the second by .030, then the third by .045,…and so on.

For example, Mary goes to bed by 3:00 am with a BAC of .020. By 10:00 am, her BAC is down to .095 (legally intoxicated) which means she would still get pulled over and get charged for DUI. By 4:00 pm the next day, she still has a BAC of .005.

BAC Level Laws

Whether a person’s BAC or Blood alcohol levels are legal or not may vary from state to state. Many states have an average level of .08 before being charged, most commonly with a Driving Under Influence crime.

Couple of whisky glasses & car keys on a table

According to Circuit Court Clerk of Will County, if the BAC levels reach .08 percent or more, a person can be charged with driving under influence of alcohol.

According to Illinois, even though the BAC does not exceed .08 percent, they may still be charged with DUI (Driving Under Influence) if pulled over, and their level measures between .05 to .08 percent.

This is a renewed law as previously, Illinois’ legal blood alcohol level used to be as high as 0.11 percent. A thorough examination depends on the police officer who will observe from demeanor, behavior, and basic abilities.

They may also question about the last location, the next location, and if the person has recently consumed any alcohol. After evaluation and observation on how the answers are delivered (Whether speech is slurred, blurry memories, or difficulty in focus), the police may ask for further examination such as sobriety tests and/or chemical testing. Failure in any of these procedures may result in a criminal DUI charge.

Related: How to beat your DUI?

Blood Alcohol Level Evaluation

In the procedure, those charged with DUI crimes must undergo several evaluations especially those caught in the state of Illinois. Conducted by the Department of Human Services, these evaluations must be taken in order to “determine the extent of the defendant’s alcohol and/or drug use and its associated risk to current or future safety.” which means one’s behavior when caught during their drunken state can affect the sentence of their crime and also their future.

During the evaluation, there are four things for the IDHS (Illinois’ Department of Human Services) must review to determine a sentence which are:

  1. Objective Test score and Category
  2. Blood alcohol content test results
  3. Driving history
  4. The result of a brief interview will be done by the end of the evaluation which mostly concerns previous drug and/or alcohol use and cross-examinations between evidence and statement.

Sometimes a urine sample is also necessary. After everything is determined, a sentence usually falls into four categories concerning the result of the blood alcohol limits.

Minimal risk is the most minor sentence and means that the accused has minimal threat on the road and will only need to complete a minimum of ten hours worth of DUI Risk Education.

Modern risk means 10 hours plus another minimum of 12 hours of early intervention. It must occur in a minimum of four weeks and a maximum of three hours per day in any seven consecutive days.

Significant risk means completing 10 minimum hours of DUI Risk Education and also a minimum of 20 hours of substance abuse treatment and some activities regarding as an ongoing care plan.

High risk is the highest sentence and poses a threat to society and would need to complete a minimum of 75 hours of substance abuse treatment and all activities specified in an ongoing care plan.

Types of Blood Level Tests

Most tests are done by police officials in order to determine if someone is under the influence of alcohol. This is most commonly done in order to charge someone with Driving Under Influence (DUI) and even if the blood alcohol limit of a person is under the current state’s legal limit, someone may still be charged if they show clear visible unstable condition or if they fall under a state’s zero-tolerance law (Under the drinking age or have underage people in the vehicle) and would need to do multiple tests in order to determine if someone needs to be charged or not.

Other than authorities doing sobriety tests and doctors trying complicated blood tests, a person can also use a few methods in order to test their blood alcohol level limit such as self-assessment as to the simplest but also considered as one of the poorest methods to use when already intoxicated.

If experiencing or seeing anyone with any behavioral change such as slurred speeches, dramatic mood swings, or rash decisions, chances are they may be heavily intoxicated. An obvious option is to simply keep intoxicated people out from driving vehicles however, this may be difficult when they’re alone or unable to give rational responses.

Another method would be the “One Drink Per Hour Rule” where, just as the name suggests, only gives the option of one drink per hour. It’s free and convenient to use although it still has many drawbacks. Since it lacks accurate calculation of BAC, it’s difficult to figure out how much exactly someone has drunk. Not only that but also the fact that every drink has a different level of alcoholic substances, and the strength also depends on personal taste and mixes.

How to Prevent getting charged with a DUI?

Guy doing a breath test inside his car

The most costly yet the most effective method in order to determine an accurate level is to simply consider buying a breathalyzer. With BACtrack’s help, modern breath testing tools are the most reliable way in order to determine someone’s blood alcohol levels accurately, especially with its many features that can be used in order to input someone’s personal information such as health history, current medications consumed, and a general food chart.

These are commercially available on the market and don’t cost as much as one would assume despite the modern technology they use that even rivals the devices issued for authority uses.

Lightweight and portable, these devices are guaranteed to provide accurate results compared to the previous methods and are also generally used by enforcement officers for roadside testing.

It also gives off immediate results which are also a convenience for those who are about to override their blood alcohol levels. They’ll easily see how much they’ve started to consume and would be able to make rational choices just before they reach a legal level of toxicity.

After reading this thorough guide on Blood Alcohol Levels, it’s necessary to know that bringing someone out when drinking is a recommendation, even better if they aren’t drinking. That way, there’s at least a person who can bring the intoxicated home safely while also avoiding the risk of DUI crimes.

If someone’s blood-alcohol level limit is already enough to endanger themselves and others around them, let them have a rest and wait until they’re at least sober enough to get home.

Contact our Experienced DUI Lawyers Today!

If caught, getting a DUI attorney in order to lower a sentence is a great way so that an accused may get a lighter sentence or one that is suited to their actual deeds without complete objectivity.