AlcoInsights estimates Blood Alcohol Content using the Widmark equation, published by Swedish chemist Erik Widmark in 1932 and still the reference method in forensic toxicology: BAC (‰) = (A / (r × W)) − (β × t), where A is grams of pure ethanol, r is the Widmark distribution ratio (~0.68 male / 0.55 female, adjustable via presets), W is body weight in kilograms, β is the elimination rate (default 0.15 ‰/h; adjustable 0.10–0.20 ‰/h), and t is hours since drinking started. Absorption is modeled as a 30-minute linear window per drink with about 10% instant absorption. Elimination is zero-order and cannot be accelerated by coffee, cold showers, or exercise (NIAAA). Known sources of uncertainty include food and stomach emptying, hydration, medications, hormonal cycle, chronic tolerance, and mis-reported drink size and ABV. Standard-drink definitions vary by region: United States 14 g, United Kingdom 8 g (1 unit), Sweden 12 g, Canada 13.6 g, Australia 10 g, Denmark 12 g, France 10 g. AlcoInsights is not a substitute for a breathalyzer and should never be used to decide whether you are safe to drive. Sources: Widmark (1932), NIAAA, WHO Global Status Report on Alcohol and Health 2024, CDC, Garnett et al. (2019) PubMed.