Blood Alcohol Concentration (BAC) Calculator
Estimate your current BAC percentage, legal driving impairment status, and time required to reach 0.00% sobriety.
Important Safety Notice: This calculator is an educational estimation based on average metabolic clearance rates. Individual factors such as stomach contents, medication, liver function, and genetics cause significant variance. Never drink and drive. If you have consumed alcohol, always arrange designated transport.
Mild impairment of rapid reaction time, divided attention, and tracking ability.
Physiological Impairment Stages & Blood Alcohol Levels
Clinical stages of alcohol influence established by forensic toxicologists:
| BAC Level (%) | Clinical Stage | Physiological & Cognitive Effects | Driving Impairment |
|---|---|---|---|
| 0.020% – 0.039% | Subtle / Mild Euphoria | Slight muscle relaxation, mild mood elevation, feeling of warmth | Decline in visual tracking, divided attention |
| 0.040% – 0.079% | Euphoria / Release of Inhibition | Exaggerated behavior, decreased judgment, slowed reaction times | Reduced coordination, steering impairment |
| 0.080% – 0.149% | Excitement / Legal Limit (US) | Major loss of balance, slurred speech, sensory loss, impaired memory | Unsafe to operate motor vehicles |
| 0.150% – 0.299% | Confusion / Severe Stupor | Disorientation, nausea/vomiting, severe motor ataxia, blackouts | Extremely hazardous / profound disability |
| ≥ 0.300% | Coma / Alcohol Poisoning | Loss of consciousness, depressed respiration, risk of death | Life-threatening medical emergency |
BAC Frequently Asked Questions
What is Blood Alcohol Concentration (BAC)?
Blood Alcohol Concentration (BAC) is a metric expressing the percentage of ethanol present in a person's bloodstream (grams of alcohol per 100 mL of blood, or g/dL). A BAC of 0.08% means your bloodstream contains 0.08 grams of alcohol for every 100 mL of blood.
What is the Widmark formula for calculating BAC?
Derived by Swedish physician Erik Widmark in 1932, the formula calculates BAC = [Alcohol consumed (g) / (Body Weight (g) × r)] × 100 - (β × Time (hours)), where 'r' is the gender-specific volume of distribution (0.68 for men, 0.55 for women) and 'β' is the average hepatic elimination rate (0.015% per hour).
What defines a standard drink?
In the United States, a standard drink contains exactly 14.0 grams (0.6 fluid ounces) of pure ethanol, which corresponds to 12 oz of standard beer (5% ABV), 5 oz of wine (12% ABV), or 1.5 oz of 80-proof distilled spirits (40% ABV).
How fast does the body metabolize alcohol?
The liver metabolizes alcohol at a relatively constant linear rate (zero-order kinetics) of approximately 0.015% BAC per hour (roughly one standard drink per hour for an average adult). Coffee, cold showers, and exercise do not accelerate hepatic alcohol dehydrogenase clearance.
Scientific References & Peer-Reviewed Literature
- Widmark EMP. (1932). Die theoretischen Grundlagen und die praktische Verwendbarkeit der gerichtlich-medizinischen Alkoholbestimmung. Fortschritte der naturwissenschaftlichen Forschung, Heft 11. Berlin: Urban & Schwarzenberg.
- Forrest ARW. (1986). Estimation of body alcohol levels: A modified Widmark equation. Science & Justice, 26(4), 249–252. PMID: 3772879.
- Jones AW. (2010). Evidence-based survey of the elimination rate of ethanol from blood with applications in forensic casework. Forensic Science International, 200(1-3), 1–20. PMID: 20434857.
- National Institute on Alcohol Abuse and Alcoholism (NIAAA). (2021). Overview of Alcohol Consumption and Standard Drink Definitions. National Institutes of Health.
