BAC Calculator
Estimate blood alcohol content using the Widmark formula. For educational use only.
This calculator provides estimates for educational purposes only. Never drive after drinking. Actual BAC depends on many factors including food, medication, and individual metabolism.
This tool is for informational and educational purposes only. It is not a substitute for professional financial, medical, legal, or engineering advice. See Terms of Service.
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This calculator uses the Widmark formula to estimate blood alcohol content:
- Select your biological sex. The Widmark formula uses different body water distribution ratios for males (0.73) and females (0.66), which affects how alcohol is distributed in the body.
- Enter your weight. Heavier individuals have more body fluid, which dilutes alcohol more.
- Enter the number of standard drinks. One standard US drink contains 14 grams (0.6 fl oz) of pure alcohol, equal to 12 oz of 5% beer, 5 oz of 12% wine, or 1.5 oz of 40% spirits.
- Enter hours since your first drink. The body metabolizes approximately 0.015% BAC per hour.
Results show your estimated BAC, impairment level, and estimated time until you reach 0.00 BAC. This is for educational purposes only.
About BAC Calculation
Blood alcohol content measures the percentage of alcohol in your bloodstream. A BAC of 0.08% is the legal driving limit in the United States and many other countries. At 0.08%, most people experience impaired judgment, reduced reaction time, and degraded coordination, which is why it is illegal to operate a vehicle at or above this level.
The Widmark formula is a widely used mathematical model developed by Swedish physician Erik Widmark. It accounts for body weight, biological sex, number of drinks, and time elapsed. However, BAC is also affected by food consumption, individual metabolism rate, medications, fatigue, and other factors that the formula cannot account for. This tool provides estimates, not clinical measurements.
Frequently Asked Questions
What counts as one standard drink?
In the United States, one standard drink contains 14 grams (0.6 fluid ounces) of pure ethyl alcohol. This is equivalent to 12 ounces of regular beer at 5% ABV, 5 ounces of wine at 12% ABV, or 1.5 ounces of distilled spirits at 40% ABV. Craft beers, stronger wines, and cocktails may contain more than one standard drink. Many restaurant pours exceed a single standard drink.
How long does it take to sober up?
The liver metabolizes alcohol at approximately 0.015% BAC per hour for most people, regardless of body size. This means a BAC of 0.10% takes about 6.7 hours to reach zero. Coffee, food, cold showers, and other popular remedies do not speed up this process. Only time reduces BAC. The time shown in this calculator is the estimated time for your BAC to reach 0.00%.
What BAC level is considered drunk?
Impairment begins at very low levels. At 0.02-0.03%, relaxation and mild mood elevation occur. At 0.05-0.08%, judgment and coordination are noticeably impaired. At 0.08%, driving is illegal in the US and most countries. At 0.15% and above, significant impairment including loss of balance and slurred speech is typical. At 0.30% and above, unconsciousness and potentially fatal outcomes become possible.
Why does body weight affect BAC?
Heavier people generally have more total body fluid. Alcohol distributes into body water, so a larger volume of fluid dilutes the same amount of alcohol to a lower concentration. A 120-pound person and a 200-pound person drinking the same amount will have very different BAC levels, with the lighter person reaching a significantly higher BAC. Body composition also matters: muscle holds more water than fat, so two people of the same weight with different body compositions may have different BAC levels.