# How Does a Blood Alcohol Calculator Work?

[caption id="attachment_596" align="alignright" width="300"] Photo Credit: U.S. Coast Guard[/caption]
A Blood Alcohol Calculator is a chart that can help you determine whether or not you are taking a chance, after having some drinks, and you decide you want to drive home, or drive period. But why is it that Jim can have one whole drink and be able to drive while Johnny can only have half a drink? It all has to do with body mass. Let's explain a little more.
The definition of blood alcohol content is the concentration of alcohol in a person’s bloodstream, expressed as a percentage. Blood alcohol content, or BAC, is used to determine whether a person is legally drunk, and is generally used to enforce the driving while intoxicated law. This law was put in place to protect people from driving under the influence of alcohol, which can endanger their lives and those of others on the roads and sidewalks. People should never drink and drive, but they sometimes do, and a Blood Alcohol Calculator might help them determine if they are under the legal limits.
The majority of motorists are not equipped with a Breathalyzer Digital Alcohol Detector like police officers carry, because they cost hundreds of dollars, and the pocket or keychain sized breathalyzer that are sold fairly cheaply, are grossly inaccurate, so... the blood alcohol calculator, while not state-of-the-art, can truly save lives.
[caption id="attachment_597" align="alignleft" width="300"] Photo Credit: Czarina Alegre[/caption]
The BAC is measured as mass per volume measured by dividing grams of alcohol in an individual's system by 100 milliliters of blood. This is then turned into a percentage. For example, in California as well as many other states, the highest legal BAC level a motor vehicle operator can have is .08%. This would mean that for every 100 ml of blood in that individuals body, there are 8 grams of alcohol in the blood stream.
So, a BAC chart will enable you to “estimate” based on your weight, and how many drinks you have had, and during what time frame, whether or not you should stay where you are, take a taxi, or let someone else drive.
When in doubt, don’t do it! Don’t drive, don’t jump off the third floor balcony into the swimming pool, and don’t attempt anything that can put you in the emergency room.