BAC Calculator
Estimate your current Blood Alcohol Concentration (BAC) and calculate how many hours remain until your body metabolizes all alcohol. Based on the widely accepted Widmark chemical distribution model, this tool incorporates biological sex, body mass, beverage count, and elapsed time.
Biological sex determines ethanol distribution volume into bodily water
Current body mass in kilograms
1 standard drink = 14g pure alcohol (12 oz 5% beer, 5 oz 12% wine, or 1.5 oz 40% spirits)
Total hours passed since you began consuming alcohol
Blood Alcohol Concentration expressed as grams of alcohol per 100 mL of blood
How to Use This Calculator
- Select your biological sex and enter your body weight in kilograms.
- Tally the total number of standard drinks you have consumed.
- Enter the total elapsed time in hours since taking your first sip.
- Examine your current estimated BAC, impairment level, and hours until sober.
Formula & Calculation Methodology
The Widmark equation calculates peak blood alcohol concentration based on the distribution ratio (r = 0.68 for men, 0.55 for women) and subtracts an average metabolic elimination rate (β = 0.015% per hour).
Worked Example
A 75 kg male who consumed 3 standard drinks over 2 hours
Frequently Asked Questions
What qualifies as one "standard drink"?↓
In the United States and Canada, one standard drink contains exactly 14 grams (0.6 fluid ounces) of pure ethanol. This equals 12 oz of 5% ABV beer, 5 oz of 12% ABV wine, or 1.5 oz of 40% ABV distilled spirits. In the UK, one unit is defined as 8 grams of alcohol.
Can coffee, cold showers, or exercise sober you up faster?↓
No. These are common misconceptions. Over 90% of alcohol metabolism occurs via liver alcohol dehydrogenase and aldehyde dehydrogenase enzymes at a fixed biological rate (approximately 0.015% per hour). Only the passage of time reduces BAC.
Why do women tend to reach a higher BAC than men after consuming identical drinks?↓
Women generally possess lower average total body water percentages (55% vs. 68% in men) and lower levels of gastric alcohol dehydrogenase enzyme in the stomach lining, resulting in higher blood concentration per unit of alcohol consumed.
Does drinking on an empty stomach increase BAC?↓
Yes. Food in the stomach delays gastric emptying into the small intestine where alcohol absorption is most rapid. Consuming alcohol with a balanced meal significantly lowers peak BAC and flattens the absorption curve.
What is the most critical limitation of any mathematical BAC calculator?↓
Formulas rely on population-average elimination constants. Individual factors such as liver enzyme polymorphisms, prescription medication interactions, fatigue, and gastric emptying rates introduce variance. Never rely on an online calculator to decide if you are safe to drive.
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Open calculator →Source Citation & Disclaimer
Informational tool only; not licensed tax, legal, or financial advice.