Free BAC calculator to estimate blood alcohol content based on drinks consumed, body weight, gender, and time elapsed since drinking.
⚠️ Important Disclaimer
This calculator provides estimates only. Individual metabolism varies significantly. Never use this to determine if you are safe to drive. When in doubt, don't drive.
Standard Drink Sizes
Beer: 12 oz (5% ABV) = 14g
Wine: 5 oz (12% ABV) = 14g
Spirits: 1.5 oz (40% ABV) = 14g
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Wondering about your BAC? This calculator estimates blood alcohol content based on drinks consumed, body weight, gender, and time since drinking. Remember: this is an estimate only—individual metabolism varies significantly.
BAC measures alcohol in your bloodstream as a percentage. 0.08% is the US legal limit for driving. Alcohol is metabolized at roughly 0.015% per hour regardless of body size. The Widmark formula estimates BAC using body weight, gender (women have lower water content), and alcohol consumed.
Widmark Formula
BAC = (Alcohol in grams / (Body weight × r)) × 100 - (0.015 × hours)This calculator is for educational purposes.
When in doubt, don't drive. Use rideshare or designated driver.
Actual BAC can vary significantly from estimates.
A standard drink contains 14 grams of pure alcohol: 12 oz beer (5%), 5 oz wine (12%), or 1.5 oz spirits (40%). Many drinks contain more—a pint of craft beer or large wine pour may equal 2+ standard drinks.