1. What is Blood Alcohol Concentration (BAC)?

Definition: BAC is a measurement of the amount of alcohol present in a person's bloodstream, expressed as a percentage.

Purpose: It helps determine legal intoxication levels and assess impairment for medical and legal purposes.

2. How Does the Widmark Formula Work?

The calculator uses the Widmark formula:

Where:

• \( BAC \) — Blood Alcohol Concentration (%)
• \( A \) — Alcohol consumed (grams)
• \( W \) — Body weight (grams)
• \( r \) — Distribution ratio (0.68 for men, 0.55 for women)
• \( \beta \) — Alcohol elimination rate (%/hour)
• \( t \) — Time since consumption (hours)

Explanation: The formula estimates how alcohol distributes in body water and accounts for metabolic elimination over time.

3. Importance of BAC Calculation

Details: Understanding BAC helps individuals make informed decisions about drinking and driving, and helps professionals assess intoxication levels.

4. Using the Calculator

Tips: Enter alcohol consumed in grams, body weight in grams, select appropriate distribution ratio (0.68 male, 0.55 female), elimination rate (typically 0.015%/hour), and time since drinking began.

5. Frequently Asked Questions (FAQ)

Q1: How do I convert drinks to grams of alcohol?
A: Multiply drink volume (ml) by alcohol percentage (as decimal) by 0.789 (density of ethanol). Example: 355ml beer at 5% = 355×0.05×0.789 ≈ 14g.

Q2: Why different ratios for men and women?
A: Women typically have higher body fat percentage and less body water, leading to higher BAC for same alcohol amount.

Q3: What's a typical elimination rate?
A: Most people eliminate 0.015% BAC per hour, but this can range from 0.01-0.025% depending on individual metabolism.

Q4: How accurate is this calculation?
A: It provides an estimate. Actual BAC can vary based on food consumption, medications, individual metabolism, and other factors.

Q5: What BAC is considered legally intoxicated?
A: In most US states, 0.08% is the legal limit for driving, but impairment begins at lower levels.