Estimate BAC by Drinks, Weight & Time
Last reviewed: April 2026
Estimate your blood alcohol content (BAC) based on drinks consumed, body weight, gender, and time elapsed. See when you'll be sober. This calculator runs entirely in your browser — your data stays private, and no account is required.
This calculator uses the Widmark formula, the standard method for estimating BAC: BAC = (Alcohol consumed in grams × 5.14) ÷ (Body weight × gender constant) − (0.015 × hours elapsed). The gender constant reflects differences in body water content (males average 73%, females 66%), which affects alcohol distribution. One standard drink contains approximately 14 grams of pure alcohol (0.6 fluid ounces). Your body metabolizes alcohol at roughly 0.015% BAC per hour — about one standard drink per hour. For related health metrics, try our BMI Calculator and Calories Burned Calculator.
At 0.02% BAC, you may feel relaxed with slightly altered mood. At 0.05%, you experience reduced coordination and lowered inhibitions. At 0.08% — the legal limit in all 50 states — reaction time, muscle coordination, and judgment are significantly impaired. At 0.15%+, you risk vomiting, loss of balance, and potential blackout. Above 0.30% is life-threatening, with risk of loss of consciousness and respiratory failure. Commercial drivers have a 0.04% limit, and under-21 drivers face zero tolerance (0.00–0.02%) in most states.
Food in your stomach slows alcohol absorption significantly — drinking on an empty stomach can double your peak BAC. Body fat percentage matters because alcohol distributes through water, not fat. Medications (especially sedatives, antihistamines, and antidepressants) can amplify alcohol's effects. Carbonated drinks (champagne, mixed drinks with soda) speed absorption. Fatigue, dehydration, and altitude also increase impairment at any given BAC level. Track your alcohol's caloric impact with our Calories Burned Calculator.
| BAC (%) | Typical Effects | Legal Status | Approx. Drinks (160 lb male) |
|---|---|---|---|
| 0.02 | Slight relaxation, warmth | Legal | 1 |
| 0.05 | Lowered inhibitions, impaired judgment | Legal (most states) | 2–3 |
| 0.08 | Impaired coordination, reaction time | DUI in all states | 3–4 |
| 0.15 | Significant impairment, slurred speech | Aggravated DUI (many states) | 6–7 |
| 0.30 | Potential loss of consciousness | Medical emergency risk | 12+ |
| 0.40+ | Life-threatening, respiratory failure | Potentially fatal | 15+ |
Blood alcohol concentration (BAC) measures the percentage of alcohol in your bloodstream by weight. This calculator uses the Widmark formula, the gold standard for BAC estimation: BAC = (alcohol consumed in grams) ÷ (body weight in grams × Widmark factor) − (elimination rate × hours since drinking). The Widmark factor accounts for body water distribution — 0.68 for males and 0.55 for females — reflecting the physiological fact that women typically have a higher body fat percentage and less body water per pound, resulting in higher BAC from the same amount of alcohol. The elimination rate averages 0.015% BAC per hour (one standard drink approximately every 75 minutes) but varies from 0.010% to 0.020% depending on liver enzyme activity, genetics, drinking frequency, and food consumption.
| BAC Level | Common Effects | Legal Status |
|---|---|---|
| 0.02–0.03% | Mild relaxation, slight warmth, mood elevation | Legal everywhere |
| 0.04–0.06% | Lowered inhibitions, impaired judgment beginning | Legal but impaired |
| 0.08% | Definite impairment of coordination and judgment | DUI/DWI in all US states |
| 0.10–0.12% | Significant motor impairment, slurred speech | Aggravated DUI in some states |
| 0.15–0.20% | Major impairment, possible vomiting, blackout risk | Enhanced penalties |
| 0.25–0.30% | Severe impairment, confusion, potential loss of consciousness | Medical emergency territory |
| 0.35%+ | Loss of consciousness, respiratory depression | Life-threatening |
A standard drink in the United States contains approximately 14 grams of pure alcohol. This equates to 12 ounces of regular beer (5% ABV), 5 ounces of wine (12% ABV), or 1.5 ounces of distilled spirits (40% ABV/80 proof). Many common servings exceed one standard drink: a pint of craft beer at 7% ABV is nearly 2 standard drinks; a generous restaurant wine pour of 8 ounces is 1.6 drinks; a strong cocktail with 3 ounces of spirits is 2 drinks. The gap between actual consumption and standard-drink equivalents is the primary reason people underestimate their BAC. When using this calculator, convert your actual drinks to standard-drink equivalents for accurate results rather than simply counting the number of beverages consumed.
The Widmark formula provides an estimate, but several factors cause real-world BAC to deviate from calculated values. Food in the stomach slows alcohol absorption by up to 50% — eating a substantial meal before drinking can reduce peak BAC by 25–35% compared to drinking on an empty stomach. However, food delays absorption without reducing total absorption — the same total alcohol eventually reaches the bloodstream but peaks lower and later. Carbonation accelerates absorption: champagne and beer with higher carbonation deliver alcohol to the bloodstream faster than still wine at the same ABV. Medications including antihistamines, anti-anxiety drugs, pain medications, and certain antibiotics intensify alcohol's effects without changing BAC. Tolerance — the neurological adaptation to regular alcohol exposure — reduces perceived impairment at a given BAC but does not reduce actual impairment of motor skills and reaction time, creating a dangerous gap between how impaired you feel and how impaired you are.
The legal BAC limit for driving is 0.08% in all US states, but impairment begins well below this threshold. At 0.05% BAC, reaction time increases by 30–50%, lane tracking deteriorates, and the ability to process multiple stimuli simultaneously (like monitoring speed, other vehicles, and road signs) is measurably reduced. Several countries including Australia, France, Germany, and Japan set their legal limit at 0.05% — and research supports this lower threshold as more aligned with actual impairment onset. For commercial drivers in the US, the legal limit is 0.04%. For drivers under 21, most states enforce zero-tolerance policies (typically 0.01–0.02%). Beyond criminal penalties (license suspension, fines, possible jail time, mandatory education programs), a DUI conviction carries insurance consequences that persist for 3–10 years — increasing premiums by $1,000–$3,000 annually. The total cost of a first-offense DUI, including legal fees, fines, increased insurance, and lost wages, averages $10,000–$25,000.
No method accelerates alcohol metabolism — the liver processes alcohol at a fixed rate regardless of external interventions. Coffee does not sober you up; it creates a wide-awake drunk with equally impaired motor skills and judgment but reduced drowsiness, which can increase risk-taking behavior. Cold showers cause temporary alertness through the shock response but do not affect BAC. Exercise increases blood flow but does not meaningfully accelerate liver metabolism of alcohol. Eating food after drinking slows additional absorption but does not reduce alcohol already in the bloodstream. Activated charcoal, which is effective for certain poisonings, does not bind alcohol efficiently and provides no benefit after alcohol has been absorbed. Time is the only factor that reduces BAC — roughly one standard drink per 75 minutes. Planning transportation before drinking, understanding your personal BAC timeline, and using tools like this calculator to estimate when you will be below the legal limit are the most responsible approaches to alcohol-related safety. Remember that individual variation is significant — two people of the same weight can have meaningfully different BAC levels from the same amount of alcohol due to differences in body composition, enzyme activity, and genetic factors. This calculator provides an estimate, not a guarantee, and erring on the side of caution is always the safer choice when deciding whether to drive. Designating a sober driver, using rideshare services, or planning overnight accommodations before the first drink eliminates the decision entirely and removes BAC estimation from the equation of safe behavior.
| Peak BAC | Drinks (Est.) | Time to 0.08% | Time to 0.00% |
|---|---|---|---|
| 0.05% | 2–3 | Already below | 3–4 hours |
| 0.08% | 3–4 | 0 hours (at peak) | 5–6 hours |
| 0.12% | 5–6 | 2–3 hours | 8–9 hours |
| 0.16% | 7–8 | 5–6 hours | 10–12 hours |
| 0.20% | 9–10 | 8–9 hours | 13–14 hours |
Nothing accelerates alcohol elimination — not coffee, cold showers, exercise, or food. The liver processes alcohol at a fixed rate of approximately 0.015% BAC per hour. After a night of heavy drinking reaching 0.16% BAC at midnight, you would not reach the legal driving limit until approximately 5–6 AM, and would not reach 0.00% until 10–11 AM. This timeline is why morning-after DUIs are surprisingly common. The only safe strategy is allowing sufficient time based on your estimated peak BAC.
See also: BMI Calculator · Calories Burned · Water Intake · Sleep Calculator · Heart Rate Zones
→ These are estimates, not exact measurements. Individual metabolism varies ±30% based on genetics, liver health, medications, and tolerance. Never use a calculator to decide if it's safe to drive.
→ Women metabolize alcohol differently. Due to lower body water percentage and less gastric alcohol dehydrogenase, women typically reach higher BAC than men at the same weight and drink count.
→ Medications interact with alcohol. Antihistamines, antidepressants, and pain medications can intensify impairment beyond what BAC alone suggests. Check interactions with your pharmacist.
→ Plan ahead for safe transportation. Designate a driver, arrange a rideshare, or stay overnight. A DUI costs $10,000–25,000+ in fines, insurance increases, and legal fees. The rideshare is always cheaper.
See also: BAC Time · Alcohol Calculator · Calorie Calculator · Budget Calculator