The main thing that influences blood alcohol concentration (BAC), of course, is how much alcohol an individual has consumed. A standard drink is generally considered to be 12 ounces of beer, 5 ounces of wine or one shot. The number of drinks that someone has is the main determinant of their blood alcohol concentration.
But there are many other factors that also play a role in an individual’s BAC. It’s important to understand how BAC is affected by a host of issues, as this understanding could ultimately impact whether or not someone gets pulled over on drunk driving allegations and/if they get convicted of impaired driving charges.
How fast alcohol is consumed
Drinking quickly can raise your BAC much faster than drinking slowly. People sometimes do this accidentally. For instance, a mixed drink may actually contain 2 to 3 shots, but a person who is imbibing may assume that they are only having “one drink.” If they drink a mixed drink with a number of shots as fast as they would drink a 12-ounce beer, they’re actually having far more alcohol than they may realize, and in a much shorter time.
Physical size and gender
Things like height and weight also play a role, in that larger individuals see their BAC go up more slowly as a general rule.
Interestingly, the impact of alcohol can be different for men than it is for women. Some of this is related to size, as women are usually a bit smaller, but there are also other factors, such as average body fat percentage. Either way, women tend to have a higher BAC after having the same number of drinks.
What is consumed before drinking
Finally, eating after drinking does not decrease someone’s blood alcohol concentration. Neither does drinking coffee or a glass of water. These are common myths. But a person’s stomach contents before they begin drinking can dilute alcohol and slow down absorption. So, someone who has a large meal before a drink may have a lower BAC than someone who drinks on an empty stomach.
Being unaware of why your BAC was higher than expected if you’re ever pulled over for impaired driving won’t help you to avoid arrest. However, under certain circumstances, it could impact your defense strategy.