Aerial photo of Montclair State University campus buildings.

Blood Alcohol Concentration

What is Blood Alcohol Concentration (BAC)?

Your body is made up of about six (6) quarts (or 5.6 liters) of blood. BAC is recorded in milligrams of alcohol in 100 milliliters of blood. A BAC of 0.10 means that 1/10 of one percent of your total blood is alcohol. This means that 1/1000 of your total blood content is alcohol. This is about 5 milliliters or a quarter of a one-quart milk container.

Body Weight

  • Weight determines how much water is in your body to dilute alcohol.

Gender

  • Men often have more body weight to dilute alcohol.
  • Women typically have 70% to 80% less of a stomach enzyme alcohol dehydrogenase, which aids in the metabolism of alcohol before it enters the bloodstream.
  • Fluctuations in hormones (related to a woman’s menstrual cycle) will also affect one’s BAC. One week before and one week after menstruating women are likely to stay intoxicated for longer periods of time.
  • Increases in estrogen whether related to one’s natural cycle or oral contraceptives (birth control pills) will likely lead to longer periods of peak intoxication than they would otherwise.

Time

  • The amount of time you spend consuming alcohol.

Amount of Alcohol Consumed

  • Knowing how to identify a standard drink is necessary for calculating blood alcohol concentrations. Please note that mixed drinks may not be measured and may contain more than 1.25/1.0 oz of alcohol. Drinks containing high proof alcohol (Everclear, grain alcohol, etc) should be treated with caution.
  • One drink is equivalent to:
    • 12 oz of Beer (4.1% Alcohol)
    • 4 oz of Wine (12% Alcohol)
    • 1.25 oz Shot (80 proof/40% Alcohol)
    • 1 oz Shot (100 proof/50% Alcohol)