What is Blood Alcohol Content and how is it measured?

Once you know the definition of one standard drink, you can estimate your Blood Alcohol Content (a.k.a. blood alcohol level; BAL). BAC levels represent the percent of your blood that is concentrated with alcohol.  A BAC of .10 means that .1% of your bloodstream in composed of alcohol.  (Loyola Marymount University)

In the United States, BAC is measured by dividing grams of alcohol by 100 milliliters of blood. This is then made in to a percentage.  In many states, the legal limit is .08%. This means that for every 100 mL of blood, there is 8 grams of alcohol in the blood stream.  (Bloodalcoholcontent.org)

What factors affect BAC?

  • How many standard drinks you drink
  • Remember different drinks have different strengths either because of differences in proofs of hard liquor or because some drinks contain more than one shot
  • Food eaten along with drinking alcohol will result in a lower, delayed BAC because the alcohol enters the bloodstream at a lower rate
  • Alcohol is attracted to areas of the body with a lot of water. Fat contains very little water, and allows more alcohol to enter the blood stream.
    • Therefore, a person with lower percent of body fat will generally have lower BACs than people with a higher percent of body fat
    • Women tend to have a higher percentage of fat and lower percentage of body water. Therefore, if a man and a woman of the same weight ingest the same amount of alcohol the women will tend to have a higher BAC.
    • Muscle contains a good amount of water. People who are more muscular tend to achieve lower BACs
  • Drinking when you are tired can lead to a higher BAC because your liver does not function as well when you are tired.
  • When you’ve been sick or are currently sick, you will be dehydrated. Dehydration has a number of effects that cause greater intoxication. Dehydration can also be a factor in how bad a hangover may be.
  • Most people can eliminate (metabolize) an average of one standard drink per hour.
  • Only time can lower your BAC. Coffee, cold showers, and runs around the block will just leave you alert, wet, and out of breath. (Loyola Marymount University)