Blood alcohol content (BAC) is a major component of establishing a person’s sobriety. When BAC is .08% or above, driving a vehicle is not only illegal but also dangerous. Each standard-sized drink increases your BAC while also elevating your level of impairment. The Centers for Disease Control and Prevention breaks down how drink size relates to BAC. 

First, you should have an understanding of how standard drink sizes are calculated. One standard drink equals about 0.6 ounces of pure alcohol. Because different types of alcohol are different potencies, standard sizes will vary depending on what you’re drinking. With wine, 5-ounces is standard because wine has a 12% alcohol content. Conversely, 1.5-ounces of 80 proof whiskey is considered standard because a whiskey has a 40% alcohol content. Beer typically has a 5% alcohol content, which means a standard-sized drink would be 12-ounces. 

Additionally, the person drinking also plays a role in BAC and drink size. Standard sizes are calculated based on how much a 160-pound man would need to drink in one hour to reach a certain BAC. A smaller man or a woman might reach a higher BAC by drinking less depending on body mass. In this case, it’s important to have strict limits in mind if you plan on drinking during a night out. Keep in mind you could become dangerously inebriated even if you’re below the legal limit. 

For example, just two drinks cause some negative effects that may impact a person’s ability to drive. At this point, a person’s BAC may be .02%, which is associated with problems with visual processing and problems multi-tasking. Four drinks bring you to the legal limit of .08%, which increases these effects and introduces new ones, like loss of short-term memory and problems concentrating. Five drinks result in a BAC of .10%, which results in problems braking or maintaining lane stability.