Blood Alcohol Percentage Calculator

Widmark BAC Equation:

\[ BAC = \frac{A \times 5.14}{W \times r} - 0.015 \times H \]

Alcohol Consumed (A):

grams

Weight (W):

lbs

Gender:

Hours Since Drinking (H):

hours

Blood Alcohol Content (BAC):

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1. What is the Widmark BAC Equation?

The Widmark equation is a mathematical formula used to estimate blood alcohol concentration (BAC) based on the amount of alcohol consumed, body weight, gender, and time since drinking began. It was developed by Swedish professor Erik M. P. Widmark in the 1930s.

2. How Does the Calculator Work?

The calculator uses the Widmark equation:

\[ BAC = \frac{A \times 5.14}{W \times r} - 0.015 \times H \]

Where:

\( A \) — Total alcohol consumed in grams
\( W \) — Body weight in pounds
\( r \) — Widmark factor (0.73 for men, 0.66 for women)
\( H \) — Hours since drinking began
5.14 — Conversion factor for pounds and grams
0.015 — Average alcohol elimination rate per hour

Explanation: The equation estimates BAC by calculating alcohol distribution in body water and accounting for metabolic elimination over time.

3. Importance of BAC Calculation

Details: BAC estimation is crucial for understanding impairment levels, legal limits for driving, and making informed decisions about alcohol consumption and safety.

4. Using the Calculator

Tips: Enter alcohol consumed in grams (1 standard drink ≈ 14 grams), weight in pounds, select gender, and hours since drinking began. All values must be valid positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: How accurate is the Widmark equation?
A: It provides a reasonable estimate but individual variations in metabolism, food intake, and other factors can affect actual BAC.

Q2: What is the legal BAC limit for driving?
A: In most US states, the legal limit is 0.08% for drivers 21 and over, and 0.02% for drivers under 21.

Q3: How do I convert drinks to grams of alcohol?
A: One standard drink contains about 14 grams of pure alcohol (12 oz beer, 5 oz wine, or 1.5 oz spirits).

Q4: Why is the elimination rate 0.015% per hour?
A: This is the average rate at which the liver metabolizes alcohol, though individual rates can vary from 0.010% to 0.025% per hour.

Q5: What factors can affect BAC accuracy?
A: Food consumption, medication, fatigue, individual metabolism, drinking rate, and body composition can all influence actual BAC levels.