# Blood Alcohol Content (BAC) Calculator Estimate your blood alcohol content with our free BAC calculator. Uses the Widmark formula to calculate BAC based on drinks, weight, gender, and time. ## What this calculates This calculator estimates your Blood Alcohol Content (BAC) using the Widmark formula, the most widely used method for BAC estimation. Enter your details to see your estimated impairment level and time until sober. ## Inputs - **Gender** — options: Male, Female - **Body Weight** (kg) — min 30, max 250 - **Number of Standard Drinks** — min 0, max 30 — 1 standard drink = 14g of pure alcohol (12oz beer, 5oz wine, 1.5oz spirits) - **Time Since First Drink** (hours) — min 0, max 24 ## Outputs - **Estimated BAC** — formatted as percentage — Estimated blood alcohol concentration - **Assessment** — formatted as text — Impairment level with driving guidance. Any non-zero BAC affects judgment and reaction time. - **Estimated Time to 0.00%** — formatted as text — Approximate hours until BAC reaches zero - **Absorption Note** — formatted as text — Widmark assumes fully absorbed alcohol; rapid drinking means your real BAC is still climbing. ## Details Blood Alcohol Content (BAC) measures the percentage of alcohol in your bloodstream. The Widmark formula calculates BAC based on the amount of alcohol consumed, your body weight, a gender-specific distribution ratio, and the time elapsed since drinking. Men typically have a higher water content in their bodies, resulting in a lower BAC per drink compared to women of the same weight. The body metabolizes alcohol at a relatively constant rate of approximately 0.015% BAC per hour, regardless of body size. This means that no amount of coffee, food, or cold showers can speed up the process. The only thing that reduces BAC is time. IMPORTANT DISCLAIMER: This calculator provides estimates only and should never be used to determine whether it is safe to drive or operate machinery. Individual BAC can vary significantly based on food intake, medications, liver function, tolerance, and other factors. When in doubt, do not drive. The legal BAC limit for driving varies by jurisdiction. ## Frequently Asked Questions **Q: What is a standard drink?** A: In the United States, a standard drink contains approximately 14 grams of pure alcohol. This is equivalent to 12 ounces of regular beer (5% ABV), 5 ounces of wine (12% ABV), or 1.5 ounces of distilled spirits (40% ABV). Other countries may define a standard drink differently, so check your local guidelines. **Q: How accurate is the Widmark formula?** A: The Widmark formula provides a reasonable estimate but is not perfectly accurate for any individual. It does not account for food in the stomach, rate of drinking, individual liver enzyme activity, medications, or health conditions. Actual BAC can vary by 20% or more from the estimated value. Never rely on this calculator to determine if you are safe to drive. **Q: How long does it take for alcohol to leave your system?** A: The body metabolizes alcohol at an average rate of about 0.015% BAC per hour. For example, if your BAC is 0.08%, it would take approximately 5.3 hours to reach 0.00%. This rate is relatively constant regardless of body size, though it can vary based on liver health, genetics, and other factors. There is no way to speed up alcohol metabolism. **Q: Why do women typically have higher BAC than men?** A: Women generally have a higher BAC than men of the same weight after consuming the same amount of alcohol. This is primarily because women typically have a lower proportion of body water (55% vs 68% in men), which means alcohol is distributed in a smaller volume of fluid. Women also tend to have lower levels of alcohol dehydrogenase, the enzyme that breaks down alcohol in the stomach. --- Source: https://vastcalc.com/calculators/health/bac Category: Health & Fitness Last updated: 2026-04-21