BAC Calculator — Blood Alcohol Content Estimator
Estimate your Blood Alcohol Content (BAC) based on drinks consumed, body weight, sex, and hours elapsed using the Widmark formula.
How Blood Alcohol Content Is Calculated
BAC (Blood Alcohol Content) measures the percentage of alcohol in your bloodstream by weight. A BAC of 0.08% means 0.08 grams of alcohol per 100 mL of blood. The most widely used estimation formula is the Widmark formula, which factors in the total alcohol consumed, your body weight, and a sex-based distribution factor.
r = 0.68 for males, 0.55 for females
Standard drink = 14g of pure alcohol
BAC Level Effects
| BAC Level | Typical Effects | Legal Status (US) |
|---|---|---|
| 0.02–0.03% | Slight warmth, mild mood lift | Legal to drive |
| 0.04–0.06% | Relaxation, mild impairment of judgment | Legal to drive |
| 0.07% | Impaired reaction time, judgment, coordination | Legal (barely) |
| 0.08% | Measurable impairment in most people | DUI threshold (all US states) |
| 0.10–0.15% | Slurred speech, coordination loss, memory gaps | Illegal |
| 0.20%+ | Severe impairment, possible blackout | Illegal |
| 0.30%+ | Life-threatening — loss of consciousness | Illegal / medical emergency |
Why This Is an Estimate, Not a Measurement
BAC calculators provide mathematical estimates based on population averages. Your actual BAC can vary significantly based on: food consumption (food slows alcohol absorption), rate of drinking, individual metabolic rate, medications, fatigue, hydration level, and tolerance built over time. The only accurate BAC measurement is a certified breathalyzer or blood test.