Factors Affecting BAC Measurements

Both the law and common sense tell us that driving while intoxicated is a bad idea. Florida law uses Blood Alcohol Content (BAC) to determine how intoxicated a driver is. BAC is the measure of the percent of alcohol by volume of water in someone’s body. However, many of us remain unclear as to how our BAC is affected by a given amount of alcohol, and what factors contribute to differences in BAC experienced by different people.

If you are drinking in a normal, social situation, you will generally experience your highest BAC within thirty minutes to an hour after you have finished your last drink. If you have had several drinks over a shorter period of time, or if you have recently eaten a large meal, it may take up to two hours after your last drink for all of the alcohol to be absorbed into your body.

Some people may experience something called a “two-hour BAC plateau.” During the plateau, the rate of alcohol absorption by their body is equal to the rate of elimination of alcohol by their body. Their BAC will remain the same throughout the plateau, and will only decrease once the rate of elimination of alcohol exceeds the rate of absorption by the body.

The often-cited rule of “one drink will be eliminated in one hour” is extremely general, and does not apply for a large percent of the population. In determining when it will be safe for you to drive, you need to take other factors of your physiology into consideration. Weight and sex are the two biggest determining factors in your BAC.

Your weight indicates the total volume of water contained within your body, and consequently how your BAC will be affected as the alcohol you consume is diffused within the body. In general, the more a person weighs, the more water their body contains and thus the smaller the increase in BAC after consumption of a given amount of alcohol. Someone who weighs 140 pounds and drinks a beer will see a higher increase in their BAC after half an hour than someone who weighs 200 pounds and drinks the same beer.

Sex is also a determining factor in the affect of a given amount of alcohol on an individual’s BAC. In general, women’s bodies contain more fat cells than do males of the same weight. Because fat takes the place of water in their bodies, there is less space for the alcohol to diffuse into a woman’s body. As a result, a woman may experience a greater increase in BAC from a given amount of alcohol than a man of the same weight.

If you have had a few drinks and are trying to determine whether it is safe for you to drive, you need to take into consideration how long it has been since your last drink, as well as how much and how quickly you were drinking. You also need to factor in your weight and sex – a 180 pound man will be safe to drive significantly sooner than a 120 pound woman. If you have been arrested for driving with a BAC above the legal limit, you should seek the advice of a Florida DUI lawyer.