BAC Calculator
Estimate your Blood Alcohol Content based on your drinks, weight, and time elapsed.
⚠ Disclaimer
This calculator provides estimates only and should NOT be used to determine whether you are safe to drive or perform any activity. Actual BAC depends on many individual factors not accounted for here. When in doubt, do not drive.
How the BAC Calculator Works
This calculator uses the Widmark formula, first developed by Swedish physician Erik Widmark in the 1930s and still the most widely used method for estimating Blood Alcohol Content. The formula accounts for the amount of pure alcohol consumed, your body weight, biological sex (which affects body water percentage), and the time elapsed since your first drink.
Your body eliminates alcohol at a roughly constant rate of about 0.015% BAC per hour (approximately one standard drink per hour). This metabolic rate is relatively consistent across individuals, regardless of body size.
A "standard drink" in the US contains about 0.6 oz of pure alcohol — equivalent to a 12 oz beer (5% ABV), a 5 oz glass of wine (12% ABV), or a 1.5 oz shot of spirits (40% ABV). If you're watching your health, you may also want to use our Calorie Calculator to track daily intake or the BMI Calculator to check your body mass index.
Learn More About BAC
Blood Alcohol Chart
See the effects of alcohol at every BAC level — from sober to life-threatening.
Legal BAC Limits by State
Compare DUI laws, penalties, and zero-tolerance policies across all 50 US states.
BAC Calculator for Beer
Estimate your BAC based on the number of beers, ABV, and serving size.
BAC Calculator for Wine
Calculate your BAC from wine consumption with custom ABV and glass sizes.
How Long Does Alcohol Stay in Your System?
Learn about alcohol metabolism, detection windows, and factors that affect elimination.