Calculate BAC

After enjoying a cocktail or two, that happy little buzz that soon follows is the result of alcohol in the bloodstream. The higher the alcohol content, the tipsier we get. A little alcohol is fine but too much can lead to legal or medical problems. It’s these reasons why people want to know more about how to calculate blood alcohol content.

Unfortunately, there’s no guaranteed method of calculation that works for all people or even for one person all the time. We each metabolize alcohol differently so even the best calculations can be false.

The alcohol metabolic rate in an individual varies enough that even keeping track of one’s own BAC can be tricky, too. Alcohol absorption into the bloodstream depends on many factors: what’s eaten while drinking, what type of drinks are consumed, medications taken, lack of sleep, stress, physical activity, even room temperature.

Blood alcohol content (BAC) compares the amount of alcohol in the bloodstream to the amount of water in it. Driving a vehicle when BAC is over the legal limit can lead to a DUI conviction, which isn’t a lot of fun and consequences last a very long time. It’s for this reason most people are interested in BAC.

To calculate blood alcohol content most accurately, a blood or breath test is required. In the United States, the BAC limit for driving legally is 0.08%, which means .08% of the fluid in 1 milliliter (1.06 grams) of blood is alcohol. A BAC of 0.40% will kill about 50% of all adults.

One serving (1.5 fluid ounces) of 80-proof liquor, one 12-ounce beer, and one 5-ounce glass of wine all contain .06 fluid ounces of alcohol. There are many charts available that help a person calculate blood alcohol content that use these serving sizes to determine intoxication.

These charts show the BAC level in a 140-pound person is 0.03% after just one drink. Alcohol absorption rates vary, though, and women become intoxicated at lower BAC levels than men do. After consuming three drinks, a 140-pound man will have reached the legal BAC limit of 0.08% but a woman will be legally intoxicated, with a BAC of 0.10%.

The gender difference is because every pound a man weighs is 58% water but a woman is only 49% water per pound. Her lower volume of water becomes proportionally more alcohol saturated with every serving than a man’s.

Charts that make it easy to calculate blood alcohol content can often be gotten from alcohol-awareness classes, police departments, state transportation agencies, criminal defense lawyers’ offices, and some medical facilities. These charts are usually small enough to fit into a pocket or purse for easy reference.

There are also many internet sources that provide BAC tracking services. There’s even a BAC-calculating software application for the iPhone.

For all practical purposes, these charts do calculate blood alcohol content but they do so loosely and should never be relied on completely. When a party’s in full swing, it’s easy to forget to count drinks and measurements become inaccurate. Use a chart as a guideline but rely on a designated driver or taxi service to be absolutely safe after a night on the town or at a party.