Blood Alcohol Concentration (BAC) Calculator
Instant, conservative blood alcohol concentration estimation and elimination timelines based on drinks consumed, body weight, biological sex, and elapsed time.
Awaiting Valid Inputs
Please enter your weight and drink details to view your estimated BAC.
How the Widmark Model Operates
A transparent three-step mathematical process grounded in clinical pharmacokinetics.
Pure Ethanol Mass Calculation
Every beverage volume is converted into milliliters and multiplied by its alcohol by volume (ABV) and the physical density of pure ethanol (0.789 g/mL) to obtain exact alcohol grams ($A$).
Body Water Volume Distribution
Alcohol dissolves predominantly in body water. Body weight in grams ($W$) is multiplied by biological gender distribution factors ($r$) to model theoretical peak alcohol concentration before elimination.
Zero-Order Hepatic Clearance
The liver metabolizes alcohol at an approximately steady rate (β ≈ 0.015% per hour). Elapsed time (t) subtracts metabolized alcohol, providing an educational range bounded by zero.
Estimated BAC (g/dL) = [ Pure Alcohol Mass (g) / ( Body Weight (g) × r ) ] × 100 - ( β × Elapsed Hours )Where $r$ represents the gender-adjusted water distribution factor (male avg: 0.68, female avg: 0.55) and $\beta$ is the hourly metabolic rate (0.012% – 0.020% / hr).
Engineered for Safety, Transparency & Privacy
Unlike commercial gimmicks or party apps, this platform prioritizes clinical accuracy and harm reduction.
Conservative Uncertainty Ranges
We never give false precision with a single misleading decimal. Our model projects realistic lower and upper bounds reflecting metabolic variability.
No-Driving Safety Mandate
We will never display a green "safe to drive" badge. Cognitive impairment begins well before statutory thresholds like 0.08% or 0.05%.
Zero-Tolerance Privacy
Your entries never leave your device. No user accounts, no cookie profiles, no database storage, and no tracking of sensitive lifestyle inputs.
Approved Alcohol Safety Calculators
Primary BAC Calculator
Dedicated multi-drink calculator estimating peak blood alcohol concentration, distribution ranges, and time-to-clearance models.
Open BAC Calculator →Standard Drink Calculator
Calculate pure ethanol mass (14g benchmark) and standard drink equivalents for craft beers, wines, spirits, and custom cocktails.
Calculate Standard Drinks →Alcohol Metabolism Calculator
Model hourly hepatic clearance kinetics (~0.015% per hour) and explore the biological timeline of alcohol elimination.
Model Metabolism Rate →About Our Mission
Learn about our safety-first approach, zero-tolerance privacy policy, and the public health principles behind this platform.
Read About Us →Important Questions & Safety Clarifications
Critical medical and legal context regarding blood alcohol calculations and health risks.
Explore Dedicated Calculators
Convert custom beverage pours to standard drinks or project hourly liver metabolism timelines with our standalone tools.