Drinking and Driving: Two Drinks can be Too Many
Many drivers make the mistake of following the "Two Drink rule" without paying sufficient attention to the size and alcoholic content of the drinks they are consuming before getting into their car. Any police officer working in the field will tell you that they have heard “But I only had two beers, Officer?!” more times than they can remember from incredulous drivers who cannot believe they have just blown a .08 or greater. Not realizing you were over the limit is not a valid defense for DUI/DWI, so read the article below and make sure this doesn’t happen to you.
The simple fact of the matter is, it doesn’t matter how many drinks you have, what matters is how much alcohol you have consumed and in what time period. Every state in the country has now implemented a per se limit of .08 blood alcohol content/concentration (BAC), which means that regardless of your individual tolerance to alcohol, you will be charged with a DUI if your BAC is found to be .08 or greater at the time of driving or within 2-3 hours of operating a vehicle.
To make things more complicated, the rate at which alcohol is concentrated in a person’s blood depends on their sex, weight, percentage of body fat, fitness-level, tolerance-level based on whether they are a regular drinker, how recently they ate, and so on. So it is very likely that the same sized glass of wine drunk over the same time period could lead to two very different BAC levels in two different people. You can get a rough estimate of BAC levels by using our BAC calculator.
What is fairly consistent regardless of physiological differences is the rate at which alcohol is metabolized and eliminated from the human body. This rate is on average .015 per hour. So it will take someone with a BAC of 0.15 ten hours for alcohol to be completely out of their system. This is important to remember, as someone with a 0.15 BAC could go home after the bar shuts at 2am, sleep for 5 hours, and get up for work at 7am, think they are OK to drive but in fact could still be over the limit. The notion that you can “sleeping it off” is totally false, as sleep has zero effect on how quickly alcohol is expelled from your system. Just because you no longer feel drunk or buzzed, does not mean that your BAC is below the legal limit to drive.
Other misconceptions about things that will “sober you up faster” include drinking coffee, caffeinated soda or lots of water, eating a big meal, taking aspirin, acetaminophen or ibuprofen, and so on. These things will have zero affect on your BAC, even you feel more sober. The only thing that makes a difference to your blood alcohol content level is time.
When deciding whether or not to drive, you should also consider the fact that many bars and restaurants do not measure out alcohol in precise serving sizes. In fact, many take a “free-pour” approach to serving alcohol. So even though you may have only drunk one margarita, it is virtually impossible to know how much tequila, triple sec, and other strong liquors were used to make it. A lot of bars and restaurants offer small and large beer glass sizes, meaning just one stein (24oz) of average strength beer could leave you above the limit. If you are drinking a stronger beer, like a stout, you could be way above the limit after just one.
We have included below a chart outlining estimated blood alcohol content levels by weight and number of drinks consumed. This chart is for reference only. Given the number of factors at work in influencing your legality to drive on a particular occasion, the safest rule to follow is, if you have the slightest doubt, don’t drive.
A standard drink is:
- A 12-ounce bottle or can of regular beer
- A 5-ounce glass of wine
- A drink of one and 1/2 ounce of 80 proof distilled spirits (either straight or in a mixed drink)
Once you have found your estimated BAC based on weight and number of drinks consumed, you need to subtract the percent of alcohol eliminated during the time elapsed since you started drinking. E.g. for a 180 lb. man - 8 drinks in 4 hours / .167% minus (.015x4) = .107 %
We’re guessing the last thing you want to do when out drinking is solving math problems, so take the safest option and don’t drive!