What is BAC?

June 25, 2018

Chances are, you’ve heard the term “BAC” or “blood alcohol content” in one way or another. But, what is BAC?

In this post, we’re going to break down what BAC means and help you understand how this acronym plays a role in alcohol-related incidents. Let’s dive in.

What Does BAC Stand For?

BAC stands for blood alcohol content, or blood alcohol concentration. A person’s blood alcohol level, or BAC, is used to measure their alcohol intoxication. In the United States, a person’s BAC will be used for both legal and medical purposes.

A BAC measurement is expressed as a percentage of alcohol in the blood. As an example, if a person has a .15 BAC, it means that .15 percent of their total blood volume is alcohol. While just a fraction of one percent might not seem like a lot, it means the person actually has quite a bit of alcohol in their system, and it will take some time for their body to absorb it.

For instance, you are considered legally intoxicated in the United States if your BAC is 0.08 percent or higher. You can actually still be convicted of a DUI offense even if your BAC is under 0.08 percent.

BAC gives law enforcement and medical professionals the ability to objectively estimate the level of a person’s alcohol intoxication. The higher a person’s BAC — the greater their impairment.

How is BAC Measured?

A person’s BAC is typically measured through one of three tests: breath, urine, or blood. While blood testing is considered to be the most accurate method of estimating BAC, a trained professional has to conduct the blood-drawing procedure. This doesn’t offer quick results, as it is much more of a time-consuming endeavor.

Meanwhile, urine tests are the least accurate, and typically only used when the other options are not available.

The most common, convenient, quick and easy method used to measure and estimate BAC is through a breath test. This is the method most often used by law enforcement in the field, as they are able to conduct roadside tests with a breathalyzer. A breath test is nearly as accurate as a blood test, and the results are considered admissible evidence in most court proceedings.

Factors That Affect a Person’s BAC

There are many factors at play that may affect a person’s BAC. This may include the person’s weight, gender, metabolism, use of any medications, the number of drinks consumed, and the rate at which they drank the alcohol. A general rule as the first factor: the faster a person consumes alcohol, the higher their BAC.

On average, men have a higher percentage of water in their bodies than women, which gives men the ability to drink more alcohol than women before they will feel impaired. Those who weigh more will also have more water in their bodies, meaning it will take more alcohol for them to become intoxicated as well.

Metabolism will vary from person to person and has its own set of underlying factors, such as body temperature and the type of alcohol and food being metabolized in their system. But in general, the slower the body metabolizes, the higher a person’s BAC. Certain prescription and over-the-counter medications can also enhance the effects of alcohol.

A common misconception with regards to alcohol consumption is that a person can sober up by eating food to soak up the alcohol or by drinking coffee. Neither of these methods ring true, as there is no way to dilute the amount of alcohol already in the body by eating or drinking non-alcoholic items. The only thing that will actually lower a person’s BAC is time.

You can slow alcohol absorption by drinking on a full stomach, however, the meal must be eaten before the person drinks alcohol.


Since there are so many factors at play, the best way to keep your BAC within the legal limit is to drink in moderation. You can refer to a blood alcohol content calculator to estimate your BAC if you think you may need to arrange alternate transportation. When it comes to alcohol, it is always best to play it safe and never drive intoxicated.


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