What Is BAC?
BAC (Blood Alcohol Concentration) is the measurement of alcohol present in the bloodstream. It is sometimes referred to as blood alcohol level or blood ethanol level.
BAC is one of the most common ways to assess how alcohol affects the body and behavior. However, the degree of impairment can vary significantly between individuals, even when their BAC levels are the same.
The most accurate way to measure BAC is through a blood test. Urine and breath tests can provide reasonably accurate results but are generally less reliable. Online BAC calculators should be used only for informational purposes—they provide rough estimates and cannot account for important factors like individual metabolism, stomach contents, body fat percentage, drinking frequency, medications, or health conditions such as alcohol use disorder.
BAC Calculator (Example)
To estimate BAC, calculators often use the following inputs:
- Gender: Female / Male / Non-binary
- Measurement type: U.S. or Metric
- Weight (lbs or kg)
- Number of standard drinks
- Hours since last drink
Definition of a standard drink (U.S.):
- 12 oz. of beer (≈ 5% ABV)
- 5 oz. of wine (≈ 12% ABV)
- 1.5 oz. of distilled spirits (≈ 40% ABV)
⚠️ Important: These results are only estimates. No chart or calculator can be 100% accurate since alcohol affects everyone differently. The safest choice after drinking is never to drive.
BAC Levels and Impairment
Here is a general breakdown of BAC levels and their typical effects:
| BAC Level | Effects from Alcohol |
|---|---|
| 0.00 – 0.03 | No loss of coordination. Mild relaxation, lightheadedness, slight euphoria. Inhibitions begin to loosen, and moods may intensify slightly. Legal limit for driving in most states. |
| 0.04 – 0.06 | Judgment, reasoning, and memory begin to be impaired. Relaxation increases, inhibitions lessen. Emotions (happiness, sadness) are more pronounced. |
| 0.07 – 0.09 | Euphoria with reduced caution and self-control. Impaired reasoning and judgment. Riskier behavior becomes more likely. |
| 0.10 – 0.12 | Strong euphoria, but balance, coordination, memory, and motor skills are significantly impaired. Speech may slur; some people become aggressive or overly emotional. |
| 0.13 – 0.16 | Severe impairment of motor skills, vision, speech, and perception. Reaction time slows dramatically. Person appears very drunk. |
| 0.17 – 0.19 | Incapacitation begins. Nausea is common. Difficulty focusing on objects; many people pass out. |
| 0.20 | Confusion, disorientation, dizziness. Walking or standing requires help. Vomiting is common, but impaired gag reflex raises choking risk. |
| 0.25 | All physical, sensory, and mental functions are severely impaired. High risk of accidents, choking, or injury. |
| 0.30 | Person may not recognize surroundings or people. Risk of sudden unconsciousness and difficulty waking up. Body becomes unresponsive to most stimuli. |
| 0.40+ | Life-threatening. Complete unconsciousness or coma is likely. At this level, BAC resembles surgical anesthesia. Death is possible. Often considered a lethal BAC. |
