Calculate your estimated blood alcohol content (BAC) based on the number of drinks consumed, body weight, biological sex, and body type. This free interactive BAC calculator uses the Widmark formula — the gold standard in forensic toxicology — with regional unit standards for Sweden (12g), UK (8g), USA (14g), Canada (13.6g), Australia (10g), Denmark (12g), and France (10g). How the calculator works: enter the number of standard drinks you've consumed, your weight in kilograms or pounds, select your gender and body type preset (which determines the Widmark r-factor), and the calculator estimates your current BAC in per mille (‰) or percent (%). It also shows your time to legal driving limit and time to zero BAC. The Widmark formula calculates BAC as: BAC = (alcohol in grams) / (body weight × r-factor) − (elimination rate × hours). The r-factor accounts for the proportion of body water — typically 0.68 for males and 0.55 for females. Body type presets in AlcoInsights range from "very conservative" (lower r, higher BAC estimate) to "very athletic" (higher r, lower BAC estimate). Important: this calculator provides estimates for educational purposes only. Actual BAC varies based on genetics, food intake, hydration, medications, and liver health. Never use BAC estimates to make decisions about driving. Legal BAC limits for driving vary: 0.2‰ in Sweden, 0.5‰ in most of Europe, 0.8‰ in the US and UK. Sources: Widmark (1932), NIAAA standard drink definitions, WHO.