Blood Alcohol Content (BAC) & Sobriety
Estimate blood alcohol concentration (BAC) and time to reach sobriety using the Widmark formula based on drinks consumed, body weight, and elapsed time.
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Drinks Consumed
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Physiological Effects & Driving Caution
Mild relaxation, slight warmth, and minor reduction in caution or fine motor coordination. Even at BAC levels below statutory legal driving limits, reaction times, visual tracking, and divided attention are measurably impaired.
Calculation Breakdown
About this tool
How to use it
- Select your biological sex (to apply the clinical Widmark gender body water factor) and enter your current body weight.
- Adjust the drink counters for beers, wine glasses, distilled spirit shots, or add custom drink volumes and ABVs.
- Enter the total hours elapsed since you took your first sip of alcohol.
- Click Calculate BAC & Sobriety to review your estimated blood alcohol concentration, metabolic clearance timeline, and hours to complete sobriety.
Why it matters
Alcohol is eliminated by the liver at a steady biological rate of approximately 0.015% BAC per hour. Calculating your estimated blood alcohol concentration and clearance timeline helps prevent driving under the influence and illustrates the substantial time required for the body to metabolize ethanol.
When to use it
Use this calculator before social outings, when reviewing previous drink consumption over an evening, or to understand how weight, biological sex, and beverage volume influence alcohol absorption and clearance times.
Good to know
Theoretical Widmark estimates provide mathematical population averages. Real-world BAC varies significantly based on stomach food content, individual liver enzyme variations (ADH and ALDH), hydration, body composition, and medications. Never use mathematical estimates to decide whether it is safe to drive or operate machinery.
Common questions
How accurate is the Widmark formula for estimating BAC?
The Widmark formula is the established forensic and scientific benchmark for estimating theoretical blood alcohol concentration based on body mass and volume of distribution. However, individual metabolism fluctuates based on whether alcohol was consumed with food, individual gastric emptying rates, body fat percentage, and genetic variations in liver enzymes.
How long does it take for your BAC to drop to zero?
The human liver metabolizes alcohol at a remarkably constant average rate of approximately 0.015% BAC per hour (equivalent to roughly one standard drink per hour). If your peak BAC reaches 0.08%, it typically takes between 5 to 6 hours from the start of elimination to reach complete 0.00% sobriety.
Can coffee, cold showers, or exercise speed up alcohol metabolism?
No. Neither caffeine, cold showers, strenuous exercise, nor drinking water increases the rate at which liver alcohol dehydrogenase (ADH) enzymes metabolize ethanol. Caffeine may temporarily increase subjective alertness, but your BAC, reaction speeds, and motor impairment remain unchanged.
What is the legal driving BAC limit in different countries?
In the United States and England/Wales, the statutory legal limit for non-commercial adult drivers is 0.08% (0.80 g/L). In Scotland, Australia, New Zealand, and most European Union nations, the statutory limit is stricter at 0.05% (0.50 g/L), with zero-tolerance limits (0.00%–0.02%) for commercial drivers and novices.
How does eating food affect blood alcohol concentration?
Eating food—especially carbohydrates, fats, and proteins—before or while drinking closes the pyloric sphincter and slows gastric emptying into the small intestine, where most alcohol is absorbed. This flattens and delays the peak BAC curve, resulting in a lower maximum BAC compared to drinking on an empty stomach.