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BAC Calculator — Free 2026

Estimate your blood alcohol concentration using the Widmark formula. For educational purposes only.

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Estimated BAC
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Blood Alcohol Concentration
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Status
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Time Until Sober

How It Works

  1. Enter your details
  2. Enter drink information
  3. Read your estimated BAC
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Understanding Blood Alcohol Concentration

Blood Alcohol Concentration (BAC) measures the percentage of alcohol in your bloodstream. In the United States, a BAC of 0.08% is the legal limit for driving in all 50 states (0.05% in Utah). Even below the legal limit, alcohol impairs reaction time, judgment, and motor skills. The Widmark formula, developed in the 1930s, remains the most widely used method for estimating BAC from drinking data.

How BAC Affects the Body

At 0.02-0.03% BAC, you may feel slightly relaxed with mild mood changes. At 0.05%, judgment and inhibitions begin to decline. At 0.08% (the legal limit), muscle coordination is significantly impaired. At 0.15%, you may experience vomiting and major loss of balance. Above 0.30%, there is risk of loss of consciousness and alcohol poisoning. These effects vary considerably between individuals based on tolerance, genetics, and other factors.

Factors That Affect BAC

Beyond the number of drinks and body weight, many factors influence BAC. Food in the stomach slows alcohol absorption. Carbonated drinks may speed it up. Medications can amplify alcohol's effects. Fatigue, stress, and dehydration all worsen impairment. Women generally reach higher BAC levels than men of the same weight due to differences in body composition and metabolism. For other health metrics, explore the BMI calculator or calorie calculator.

Never drink and drive. This calculator provides estimates for educational purposes only. Actual BAC depends on many factors including metabolism, food intake, medications, and individual tolerance. Do not rely on this tool to determine whether you are safe to drive. When in doubt, do not drive. Consult a qualified medical professional for health-related decisions.
For informational purposes only. Consult a qualified professional before making health or medical decisions.

Frequently Asked Questions

What is BAC?
BAC stands for Blood Alcohol Concentration, the percentage of alcohol in your bloodstream. A BAC of 0.08% is the legal limit for driving in most US states. A BAC of 0.00% means no alcohol is present, while a BAC above 0.30% can be life-threatening.
How does the Widmark formula work?
The Widmark formula estimates BAC as: BAC = (Alcohol consumed in grams / (Body weight in grams x r)) x 100 - (0.015 x hours). The 'r' factor is 0.73 for males and 0.66 for females. The body metabolizes alcohol at approximately 0.015% BAC per hour.
How many standard drinks are in beer, wine, and spirits?
One standard drink contains about 14 grams of pure alcohol. This equals approximately 12 oz of beer (5% ABV), 5 oz of wine (12% ABV), or 1.5 oz of distilled spirits (40% ABV). Craft beers and strong wines may contain significantly more alcohol per serving.
How long does it take to sober up?
The body metabolizes alcohol at a relatively constant rate of about 0.015% BAC per hour. This means it takes roughly one hour per standard drink for your BAC to return to zero. Nothing speeds up this process — not coffee, cold showers, or food. Only time reduces BAC.

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