Calculating BAC

Understanding the effects of a rising BAC can be very useful in controlling drinking. Check out the Drink Wheel to calculate your BAC level.

The amount of alcohol in your blood stream is referred to as Blood Alcohol Content (BAC). It is recorded in milligrams of alcohol per 100 milliliters of blood, or milligrams percent. For example, a BAC of .10 means that 1/10 of 1 percent of your total blood content is alcohol. When you drink alcohol it goes directly from the stomach into the blood stream. This is why you typically feel the effects of alcohol quite quickly, especially if you haven't eaten in a while.

BAC depends on:
  1. Amount of blood (which will increase with weight).
  2. The amount of alcohol you consume over time (the faster you drink, the higher your BAC, as the liver can only handle about a drink an hour - the rest builds up in your blood stream).
Below are the effects of increasing BAC.
  • .00 This is the only safe BAC level.
  • .02 Mellow feeling, slight body warmth, less inhibited. At and above this level U.S. federal laws mandate that a person in a safety sensitive transportation job must be removed from the workplace.
  • .05 Noticeable relaxation, less alert, less self-focused, coordination impairment begins. At and above this level U.S. federal laws mandate that a person in a safety sensitive transportation job must be sanctioned and may lose their job.
  • .08 DRUNK DRIVING LIMIT in Iowa, definite impairment in coordination and judgment. At and above this level you can be convicted of driving while intoxicated. Check out the Iowa Department of Safety website.
  • .10 Noisy, possible embarrassing behavior, mood swings, reduction in reaction time.
  • .15 Impaired balance and movement, clearly drunk.
  • .30 Many lose consciousness. At this level most people will lose consciousness.
  • .40 Most lose consciousness; some die. At this level most people will become comatose and may die.
  • .50 Breathing stops and many die.

As can be seen, the most pleasurable effects of alcohol occur at about .03-.05. Alcohol researchers have discovered that low levels of alcohol have a specific effect on thinking; alcohol results in a reduction of "self-monitoring." What this means is that small quantities of alcohol enable you to take your mind off yourself and your worries. Not surprisingly, this effect reduces tension and enhances relaxation in many people. Some people find this effect so rewarding that they continue to drink. Unfortunately, the effect on self monitoring diminishes as it rises above .05. Instead emerge a host of negative effects, such as less emotional control, coordination and judgment impairment, hangovers and obnoxious behavior. Figure out what a safe limit for you is by using the Drink Wheel.