The alcohol level in the body, commonly referred to as Blood Alcohol Concentration (BAC), can be estimated using several formulas. One widely recognized formula is the Widmark formula, which is used to estimate the concentration of alcohol in the bloodstream after consuming alcoholic beverages. The formula is given by:

BAC = (Body water coefficient × Body weight in grams) / (Alcohol consumed in grams) × 100

In this formula:

  • Alcohol consumed in grams can be calculated by multiplying the volume of alcohol consumed (in milliliters) by its density (0.789 g/ml for ethanol) and the alcohol percentage by volume.
  • Body water coefficient is a factor that represents the proportion of the body made up of water, which varies by sex. Typically, this value is around 0.68 for men and 0.55 for women, but it can vary.
  • Body weight in grams must be converted from kilograms or pounds to grams (1 kg = 1000 grams).
  • The result is multiplied by 100 to convert the decimal BAC to a percentage.

Another important factor to consider is the metabolism rate of alcohol, which can be subtracted from the BAC over time. The average metabolism rate is about 0.015 BAC per hour, but this can vary from person to person.

It’s important to note that while formulas like these can provide an estimate, actual BAC can vary greatly due to numerous factors, including but not limited to individual metabolism rates, the presence of food in the stomach, and specific biological differences. Therefore, these calculations should be used with caution and not for determining whether it’s safe to engage in activities such as driving.