Blood Alcohol Concentration

Blood/Breath Alcohol Concentration (BAC) is the amount of alcohol in the bloodstream or on one’s breath. BAC is expressed as the weight of ethanol, in grams, in 100 milliliters of blood, or 210 liters of breath. BAC can be measured by breath, blood, or urine tests.

The number of drinks consumed is a very poor measure of intoxication largely because of variation in physiology and individual alcohol tolerance.

Variation exists with respect to:

  • Body weight
  • Sex
  • Body fat percentage, even between genders

Neither BAC, nor the number of drinks consumed, are necessarily accurate indicators of the level of impairment. Tolerance to alcohol also varies from one person to another, and can be affected by such factors as genetics, adaptation to chronic alcohol use, and synergistic effects of drugs.

In the state of Indiana, as in most states, you are legally intoxicated at a BAC of .08, no matter your age.

Utilize this calculator to better understand your BAC. Please remember that this is an estimation and not an exact science.

BAC-Specific Effects

BAC Level Generalized Dose Specific Effects
0.020-0.039% No loss of coordination, slight euphoria, and loss of shyness. Relaxation, but depressant effects are not apparent.
0.040-0.059% Feeling of well-being, relaxation, lower inhibitions, and sensation of warmth. Euphoria. Some minor impairment of judgment and memory, lowering of caution.
0.06-0.099% Slight impairment of balance, speech, vision, reaction time, and hearing. Euphoria. Reduced judgment and self-control. Impaired reasoning and memory.
0.100-0.129% Significant impairment of motor coordination and loss of good judgment. Speech may be slurred; balance, peripheral vision, reaction time, and hearing will be impaired.
0.130-0.159% Gross motor impairment and lack of physical control. Blurred vision and major loss of balance. Euphoria is reducing and beginning dysphoria (a state of feeling unwell)
0.160-0.199% Dysphoria predominates, nausea may appear. The drinker has the appearance of a sloppy drunk.
0.200-0.249% Needs assistance in walking; total mental confusion. Dysphoria with nausea and vomiting; possible blackout.
0.250-0.399% Alcohol poisoning. Loss of consciousness.
0.40% + Onset of coma, possible death due to respiratory arrest.

Time Factor Table

Time is the only factor to lower one’s Blood Alcohol Content. Coffee, cold showers, etc… are all myths. 

Hours since first drink 1 2 3 4 5 6
Subtract from blood alcohol level .015 .030 .045 .060 .075 .090

For example:

John Smith goes to bed at 2:00 a.m. with a BAC of .20.

  • 9:00 a.m. - When he gets up his BAC is .095 (legally intoxicated). What if he drives to class and gets pulled over for rolling through a stop sign?
  • 3:00p.m. - The next day, he still has a BAC of .005.