| BAC Range | Level | Typical Effects |
|---|---|---|
| 0.00 – 0.03 | Sober / Minimal | Normal behavior, slight mood elevation |
| 0.03 – 0.06 | Mildly Impaired | Lowered inhibitions, mild euphoria, slight impairment of judgment |
| 0.06 – 0.08 | Impaired | Reduced coordination, impaired reasoning, lowered self-control |
| 0.08 – 0.12 | Legally Intoxicated | Poor muscle coordination, impaired balance, slower reaction time, slurred speech |
| 0.12 – 0.20 | Severely Impaired | Major loss of balance, blurred vision, nausea, significant judgment impairment |
| 0.20 – 0.30 | Dangerous | Disorientation, need assistance to walk, potential loss of consciousness, vomiting |
| 0.30+ | Life-Threatening | Risk of coma, respiratory depression, and death. Seek emergency help immediately. |
What Is Blood Alcohol Content (BAC)?
Blood Alcohol Content (BAC) is the percentage of alcohol in your bloodstream by weight. A BAC of 0.08% means there are 0.08 grams of alcohol per 100 milliliters of blood. BAC is the standard measure used by law enforcement and medical professionals to assess intoxication levels.
How the Widmark Formula Works
This calculator uses the Widmark formula, the most widely used method for estimating BAC. The formula accounts for the amount of pure alcohol consumed, your body weight, a gender-based distribution ratio (the "Widmark factor"), and the time elapsed since drinking began. The body metabolizes alcohol at an average rate of approximately 0.015% BAC per hour.
The formula: BAC = (Alcohol oz × 5.14) / (Body weight lbs × r) − 0.015 × hours, where r is 0.73 for males and 0.66 for females.
What Is a Standard Drink?
In the United States, one standard drink contains approximately 14 grams (0.6 fluid ounces) of pure alcohol. This equals about 12 ounces of regular beer (5% ABV), 5 ounces of wine (12% ABV), or 1.5 ounces of distilled spirits (40% ABV). Knowing what constitutes a standard drink is essential for tracking your alcohol consumption accurately.
Factors That Affect BAC
- Body weight: Heavier individuals generally have a lower BAC after the same amount of alcohol because alcohol is distributed across more body mass.
- Biological sex: Women typically reach higher BAC levels than men of the same weight because of differences in body water content and enzyme activity.
- Food intake: Eating before or while drinking slows alcohol absorption into the bloodstream.
- Rate of consumption: Drinking faster leads to a higher peak BAC because the liver can only metabolize about one standard drink per hour.
- Medications: Many medications interact with alcohol and can amplify its effects.
- Liver health: Liver conditions can significantly slow alcohol metabolism.
Legal BAC Limits
In most US states, the legal BAC limit for drivers over 21 is 0.08%. However, impairment begins well before this threshold — studies show reaction time and decision-making are affected at BAC levels as low as 0.02%. Commercial drivers are held to a stricter 0.04% limit, and most states have zero-tolerance laws for drivers under 21.