Blood Alcohol Concentration (BAC) Calculator

Blood alcohol concentration (BAC) depends on how much alcohol was consumed, body weight, biological sex, and how much time has passed since drinking began. This calculator estimates current BAC, projects how long it will take to reach 0%, and summarizes the impairment typically associated with that range.

• Estimate current BAC from sex, weight, drink volume, ABV, and elapsed time.
• Project the time to reach 0% BAC, useful for planning safer travel and scheduling.
• Show the behavioral effects and impairments typically associated with different BAC ranges.
• Compare different drink types and serving sizes when planning responsible consumption.
• Retain inputs locally between checks during the same event, so an update does not require re-entering everything.

BAC is estimated with a Widmark-based approach, which weighs total alcohol consumed against body weight and a gender-specific distribution factor reflecting the difference in body water percentage between men and women. A typical metabolism rate of about 0.015% BAC per hour is applied to account for the time elapsed since the first drink. Preset sizes and ABV ranges cover beer, wine, and liquor, and custom values accommodate mixed drinks and nonstandard pours that fall outside those presets.

Treat the BAC figure as an estimate, not a measurement. The time to 0% BAC reflects how long alcohol may take to clear at an average elimination rate, and the behavior and impairment summary lists effects commonly associated with the result. Real physiology varies by person and situation: hydration, food intake, medications, and health status can all shift the true value away from the estimate. Do not use this calculator to decide whether you can drive or operate machinery.

Example 1: A 180-pound male, 2 hours after his first drink, with two 12 oz beers at 5% ABV, produces a moderate estimated BAC and a projected timeline to reach 0%, useful for planning a safe ride home.

Example 2: A 140-pound female, 90 minutes after her first drink, with one 5 oz glass of wine at 12% ABV and one 1.5 oz shot at 40% ABV, shows the combined effect of different beverage types and the estimated time until no alcohol remains.

Example 3: A custom cocktail entered as total fluid ounces with its own ABV shows how stronger mixed drinks can raise BAC faster than standard beer, wine, or liquor servings.

How accurate is this BAC estimate? Treat the result as a general educational estimate. Individual metabolism, timing of drinks, and personal factors can create significant differences.

What gender factor does the calculator use? A typical distribution ratio of about 0.68 for men and about 0.55 for women, which affects how alcohol distributes in the body.

What elimination rate does it assume? A standard rate of about 0.015% BAC per hour. The actual rate for any individual may be higher or lower.

Can this tell me if I can drive? No. This tool cannot determine legal fitness to drive. Laws and limits vary by location, and real impairment can occur below legal limits.

Why do results change quickly? Small changes in weight, ABV, serving size, or time can shift BAC estimates, so precise inputs and a regularly updated time field matter.

Prioritize safety over any estimate. Arrange a sober driver, rideshare, or public transit after consuming alcohol. Legal limits, enforcement policies, and penalties differ by state and country. When in doubt, do not drive. Seek medical help for signs of alcohol poisoning such as vomiting, unconsciousness, slow breathing, or bluish skin.

Estimating BAC takes four inputs: biological sex (which sets the body-water distribution factor), body weight, time elapsed since the first drink, and the serving size and alcohol by volume (ABV) of every drink consumed. One row per drink, each with its own serving size and ABV, lets the estimate account for a mix of beer, wine, and liquor rather than assuming a single drink type throughout a session.

Estimated BAC, projected time to reach 0%, and a summary of likely behavioral effects and impairments update from these values with no server-side processing, using the Widmark formula:

• BAC = (alcohol in grams / (body weight in pounds × r)) × 100, where r = 0.68 for men and 0.55 for women.
• Adjusted BAC = the greater of 0 and (BAC - 0.015 × hours since the first drink), which floors the estimate at zero rather than letting it go negative.
• Time to 0% = adjusted BAC / 0.015.

Understanding blood alcohol concentration matters in a range of everyday situations:

• Personal use by individuals who want to drink responsibly and monitor their estimated BAC.
• Educational settings for teaching students about alcohol metabolism and impairment effects.
• Event planners or hosts providing safety information to guests.
• Health professionals or counselors using it as a quick reference during consultations.

• Track drinks as they are consumed to avoid undercounting volume and ABV.
• Eat before and during drinking to slow alcohol absorption.
• Alternate alcoholic beverages with water or nonalcoholic drinks.
• Plan transportation before drinking begins, removing the choice from an impaired decision later.
• Recheck the estimate as time passes to see updated projections.

This tool is intended for informational and educational purposes only. It does not provide medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider for any health-related concerns or decisions.