Free Online Blood Alcohol Content BAC Calculator Tool
Blood Alcohol Calculator uses the Widmark formula to estimate your BAC level based on drinks consumed, body weight, gender, and time elapsed. Get instant results with impairment levels and safety guidance. Completely private, no data stored.
Calculate Your Blood Alcohol Content
How to Use the Blood Alcohol Calculator
Select Your Gender
Choose your biological gender as it affects alcohol metabolism rates due to differences in body water content.
Enter Your Body Weight
Enter your body weight in kilograms or pounds. Use the toggle to switch between KG and LBS units.
Add Your Drinks
Select the type of alcoholic beverage, enter the quantity in ml, the alcohol percentage (ABV), and the number of drinks consumed.
Enter Time Since First Drink
Enter the number of hours that have passed since you started drinking to factor in alcohol metabolism.
Click Calculate BAC
Click the Calculate BAC button to instantly see your estimated blood alcohol content, impairment level, and safety recommendations.
Key Features of This BAC Calculator
100% Free Forever
Calculate your estimated blood alcohol content unlimited times without any charges, subscriptions, or hidden fees.
Widmark Formula Accuracy
Uses the scientifically validated Widmark equation, the gold standard for BAC estimation used in forensic science worldwide.
Instant Real-Time Results
Get your estimated BAC level with impairment details and safety guidance in milliseconds, no waiting or loading required.
Complete Privacy Protection
All calculations happen in your browser. Your weight, gender, and drinking data are never sent to any server or stored anywhere.
No Signup Required
Start calculating immediately without creating accounts, verifying email, or providing any personal identification whatsoever.
Mobile-Friendly Interface
Fully responsive design works perfectly on all smartphones, tablets, and desktop computers with touch-friendly controls.
How the Widmark BAC Formula Works
BAC = (A / (W Γ r)) Γ 100 β (Ξ² Γ T)Where A = alcohol consumed (grams), W = body weight (grams), r = Widmark factor, Ξ² = metabolism rate, T = time (hours)
Calculation Components
- A (Alcohol in grams): Calculated as Volume (ml) Γ ABV (%) Γ 0.789 (density of ethanol). For example, 330ml of 5% beer = 330 Γ 0.05 Γ 0.789 = 13.02 grams of pure alcohol.
- W (Body Weight): Your body weight converted to grams. For a 70 kg person, this equals 70,000 grams. Heavier individuals generally achieve lower BAC for the same amount of alcohol.
- r (Widmark Factor): A gender-specific constant representing the ratio of body water to total weight. Males = 0.68, Females = 0.55. Women have a lower factor due to higher body fat percentage.
- Ξ² (Metabolism Rate): The rate at which the body eliminates alcohol, typically 0.015% per hour. This equals approximately one standard drink per hour for most adults.
- T (Time in Hours): The time elapsed since the first drink was consumed. The body begins metabolizing alcohol immediately, reducing BAC over time at the Ξ² rate.
For example, if Rajesh (male, 75 kg) drinks 2 pints of Kingfisher beer (each 330ml at 4.8% ABV) over 2 hours, the calculation would be: Total alcohol = 2 Γ 330 Γ 0.048 Γ 0.789 = 25.0 grams. BAC before metabolism = (25.0 / (75000 Γ 0.68)) Γ 100 = 0.049%. After 2 hours of metabolism: 0.049% β (0.015 Γ 2) = 0.019%. This puts Rajesh below India's legal limit of 0.03%, but impairment can still occur at any BAC above zero. The safest choice is always to avoid driving after drinking.
BAC Calculation Examples
Rajesh β 2 Beers After Office Party
Priya β Wine at Dinner Celebration
Amit β Whiskey at Weekend Gathering
James β Craft Beer Tasting in London
What is a Blood Alcohol Calculator?
A Blood Alcohol Calculator is an educational tool designed to estimate your Blood Alcohol Content (BAC) β the percentage of alcohol present in your bloodstream after consuming alcoholic beverages. It uses the scientifically established Widmark formula, developed by Swedish scientist Erik Widmark, which takes into account the amount of alcohol consumed, your body weight, biological gender, and the time elapsed since drinking to provide an approximate BAC reading.
This tool is valuable for anyone who wants to understand how alcohol affects their body. Whether you are a young professional in Mumbai who had a few drinks at an office party, a college student in Delhi learning about responsible drinking, or a health-conscious individual anywhere in the world, this calculator helps you understand the relationship between alcohol consumption and intoxication levels. It is especially important in India where the legal BAC limit for driving is just 0.03% β one of the strictest globally.
Our BAC calculator is built with expertise in pharmacokinetics and alcohol metabolism science. It supports multiple drink types including Indian favourites like Kingfisher beer, Old Monk rum, and imported whiskey, with accurate ABV values and standard serving sizes. Every calculation runs entirely in your browser for complete privacy. Remember, this is an estimation tool for educational awareness β it should never replace professional breathalyzer testing or medical advice, and you should never drink and drive regardless of your estimated BAC level.