Counseling Center

Blood Alcohol Content

Blood Alcohol Content (BAC) is a measure of alcohol in the blood as a percentage. It is calculated in grams per 100 mL of blood, so a BAC of 0.08 means your blood is 0.08% alcohol by volume.  Using a breathalyzer, BAC is measured as grams per 210 Liters of breath (since the ratio of breath alcohol to blood alcohol is 2,100:1).

What do you experience at different BAC levels?

The following are predictable effects we’d expect to see at different BAC levels for a drinker who has not developed tolerance.  Some of these change with tolerance; others don’t (see the page on tolerance).

BAC Effects Experienced
.02-.04% Lightheaded – Relaxation, sensation of warmth, “high,” minor impairment in judgment
.05-.07% Buzzed – Relaxation, euphoria, lower inhibitions, minor impairment of reasoning and memory, exaggerated emotions (positive and negative)
.08-.10% Legally impaired – Euphoria, fatigue, impairment in balance, speech, vision (particularly peripheral), reaction time, and hearing, judgment and self-control impaired
.11-.15% Drunk – “High” is reduced, depressive effects (anxiety, depression, unease) more pronounced, gross motor impairment, judgment and perception severely impaired
.16-.19% Very drunk – Strong state of depression, nausea, disorientation, dizziness, increased motor impairment, blurred vision, judgment further impaired
.20-.24% Dazed and confused – Gross disorientation to time and place, increased nausea and vomiting, may need assistance to stand or walk, impervious to pain, blackout likely
.25-.30% Stupor – All mental, physical, and sensory functions are severely impaired, accidents very likely, little comprehension, may pass out suddenly 
.31% and up Coma – Level of surgical amnesia, onset of coma, possibility of acute alcohol poisoning, death due to respiratory arrest likely in 50% of drinkers

Tracking BAC

The following charts can assist you in tracking your BAC while drinking. 

Female Male
Female BAC Male BAC

The Biphasic Effect 

Alcohol is a depressant, but there are actually two phases or stages that a drinker experiences.  See the red line in the graph below:

 Biphasic Effect

As BAC slowly rises and is under .055:

  • The drinker experiences mild stimulating effects such as increased heart rate, increased energy, self-confidence, sociability, and a feeling of wellbeing or "euphoria." This is the Buzz Zone.

At a BAC of .055:

  • Peak stimulation and euphoria occur. After this "Point of Diminishing Returns," higher BACs will result in fewer and fewer positive effects. You’ll feel more impaired, not better

As BAC surpasses .055:

  • The drinker begins to feel the depressant effects of alcohol such as sluggishness, fatigue, sloppiness, lack of balance, and coordination, slurred speech. To others, the drinker often appears "drunk."

Once you’ve gone beyond the "Point of Diminishing Returns," it is impossible to return to the Buzz Zone. Remaining in the Buzz Zone maximizes the drinker's positive experience and reduces harm.

Tolerance (being able to "hold one's liquor") hampers alcohol's positive effects by reducing the initial stimulant qualities (yellow line). High tolerance makes drinking more costly in terms of calories and money, limits the euphoria, and worsens the depressant effects.

A Useful Smartphone Application

 BACcards BACcards

This convenient monitoring tool will continuously track and estimate your alcohol consumption and Blood Alcohol Concentration (BAC) level over time. Simply record your drinks for an up-to-date estimate of your BAC.

*Disclaimer: This information is meant to provide education about substance use. The content of this workshop is not meant to replace therapy and is not considered mental health treatment. If you are in crisis or find yourself needing more support please call the UToledo Counseling Center at 419-530-2426 or dial 9-1-1 if it is an emergency.


Last Updated: 6/27/22