1. What is the Widmark Formula?

The Widmark formula is a mathematical equation used to estimate blood alcohol concentration (BAC) based on the amount of alcohol consumed, body weight, gender, and time since drinking. It was developed by Swedish professor Erik M. P. Widmark in the 1920s.

2. How Does the Calculator 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)
• \( \beta \) — Elimination rate (typically 0.015%/hour)
• \( t \) — Time since drinking (hours)

Explanation: The formula accounts for alcohol distribution in body water and the rate at which alcohol is metabolized over time.

3. Importance of BAC Calculation

Details: BAC estimation is crucial for understanding impairment levels, legal limits (typically 0.08% in many countries), and when it's safe to drive after drinking.

4. Using the Calculator

Tips: Enter alcohol in grams (1 standard drink ≈ 14g alcohol), weight in grams (1 lb ≈ 453.6g), time in hours, and select gender. The default elimination rate is 0.015%/hour but can be adjusted.

5. Frequently Asked Questions (FAQ)

Q1: How accurate is the Widmark formula?
A: It provides an estimate but actual BAC can vary by ±20% due to individual metabolism, food intake, and other factors.

Q2: What's considered legally drunk?
A: In most US states, 0.08% is the legal limit for driving. Commercial drivers have a 0.04% limit.

Q3: How long does alcohol stay in your system?
A: The body typically metabolizes alcohol at 0.015-0.02%/hour, so it takes about 5-6 hours to eliminate all alcohol from a 0.08% BAC.

Q4: Why is the ratio different for men and women?
A: Women generally have higher body fat percentage and lower water content, leading to higher BAC from the same alcohol amount.

Q5: Can I use this for legal purposes?
A: No, this is only an estimate. Only breath, blood, or urine tests provide legally valid BAC measurements.