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What is Blood Alcohol Concentration (BAC)?

An individual’s blood alcohol concentration also called blood alcohol content or BAC refers to the percent of alcohol in their bloodstream. The number of factors that can determine and influence the alcohol level in blood:

  • Bodyweight
    • An individual’s weight determines how much space alcohol has to diffuse throughout their body
  • Biological sex
    • Women tend to metabolize alcohol at a different rate than men
    • Research indicates that women have fewer of the enzymes required for alcohol metabolization than men
  • Medications
    • Many medications can interact negatively with alcohol or impact your body’s ability to metabolize alcohol
    • Even OTC drugs like Tylenol can have an impact
    • In some instances, interactions are fatal
  • The time frame in which you consume drinks
    • Downing large quantities of alcohol quickly or all at once push your body’s limits when it comes to metabolization
    • When you drink too fast, your cognitive system shuts down, you may vomit, and your sympathetic system shuts down
  • The number of standard drinks consumed

Many individuals find themselves lost when it comes to determining what constitutes a “standard drink.” To drink responsibly, a pragmatic approach here will generally lead you down the right path. Remember that if you are driving, there is no safe amount of alcohol you can drink. You should only get behind the wheel if you are sober. One 12 oz. regular beer, for example, is one standard drink; as are a 5 oz. a glass of wine and a 1.5 oz. shot of hard liquor.

How Various BAC Levels Increase Impairment

Different BAC levels have different impacts on your impairment level and ability to drive. If you’re uncertain when it comes to understanding what all the numbers mean, read below for an overview of how you might be feeling and how your body will be working at various BAC levels:

  • BAC of .01-.03
    • No apparent effects
    • Minimal mood elevation
    • In many states, if you’re under 21 years of age, biking or driving at this level is illegal
  • BAC of .04-.06
    • Feelings of warmth and relaxation
    • Minor impairment regarding memory and reasoning
  • BAC of .07-.09
    • Mild impairment of:
      • Speed
      • Balance
      • Control
      • Vision
    • In many states, if you are of or over 21 years of age, biking or driving at this level is illegal
  • BAC of .10-.12
    • Loss of judgment
    • Slurred speech
    • Significant impairment to motor coordination
  • BAC of .13-.15
    • Extreme loss of balance
    • Gross impairment of motor control
    • Severely impaired vision
    • Anxiety and restlessness
  • BAC of .16-.20
    • Anxiety and restlessness increase markedly
    • Nausea
  • BAC of .25-.30
    • Severe intoxication levels
    • Walking becomes impossible
    • Intense confusion
    • Vomiting
  • BAC of .35-.40
    • Loss of consciousness
  • BAC of .40 or greater
    • Onset of coma
    • Respiratory failure
    • Death

Even at a BAC .01, you should opt for a designated driver or public transportation. You could still get arrested for drunk driving even if you have a small amount of alcohol in your system. Under no circumstances should you drive at any of the BAC levels noted above; and you should take steps to ensure that nobody around you is getting behind the wheel in a similar state, either.

Learning More About BAC Limits in Your State

BAC limits and the penalties for them vary by state. For the most part, the laws surrounding the legality of drinking and driving in the United States tend to be very similar regardless of your location. Small details do vary, though, and understanding the laws for your area is paramount for safe driving.

Those interested can visit our website to learn more about DUI laws in your state; and, if you or a loved one needs an interlock device, you can contact us today. At RoadGuard Interlock, we’re committed to compassionate and respectful service; we appreciate that you have a choice in interlock devices and service providers and have paired world-class customer support with cutting-edge technology to offer quick, reliable, quality service.


*Links to any third-party websites herein are provided for your reference and convenience only. RoadGuard Interlock did not create nor develop and does not own any such third-party websites. RoadGuard Interlock does not endorse nor support the content of, nor any opinions stated in any such third-party website links. RoadGuard Interlock is not responsible for the content of any third-party website or its accuracy or reliability. Nothing contained in this article or in any such third-party website shall be considered legal advice or be deemed to constitute legal advice. For any legal advice concerning a DUI arrest, charge, conviction, or consequences thereof, you should contact an attorney of your choice.