E-BAC formula

From AODWiki

The AODWiki BAC Calculator (working example found here) uses the following formula to estimage BAC:

BAC Estimate = ((standard drinks / 2) * (gender constant / weight)) - (0.017 * hours)

The gender constant is 9.0 for females and 7.5 for males. Weight is measured in pounds, and hours is the number of hours over which the alcohol is consumed and metabolized. We are adopting the metabolism rate of 0.017 g/dl per hour which is reported by NHTSA to be the average rate. However, metabolism rates can vary from 0.010 g/dl to 0.04 g/dl.

This formula was offered by Matthews and Miller (1979)¹ and described within the paper by Hustad and Carey (2005)². Hastad and Carey found that this formula yielded the highest level of agreement between estimated BACs and breath alcohol tests among college students, using self-reported drinking, time and weight variables. It is important to remember that many factors can affect the accuracy of this formula including variations in absorption and metabolism rates. The Matthews and Miller formula differs slightly from the NHTSA BAC formula. Further, the alcohol content of drinks varies. Click here for a discussion on the definition of Standard Drinks.

References

1. Mathews, D.B., and Miller, W.R. (1979). Estimating blood alcohol concentration: Two computer programs and their applications in therapy and research. Addictive Behavior, 4, 55-60.
2. Hustad, J.T.P., and Carey, K.B. (2005). Using calculations to estimate blood alcohol concentrations for naturally occurring drinking episodes: A validity study. Journal of Studies on Alcohol, 66, 130-138.