BAC – Blood Alcohol Content, Drink Driving Limit

Without any doubt, the BAC (Blood Alcohol Content) test as it has helped the authorities to minimize the numbers of cases related to DUI offense, which in turn has also instilled a sense of fear among people who often drink more than the prescribed limit and roll down their vehicles on the road. But, how BAC is calculated and what are the other tests available? Through this article

we will help you know about some interesting facts about BAC test and its various aspects.


BAC or Blood Alcohol Level

BAC or blood alcohol content is measurement of alcohol content in your blood. So, it simply shows how deeply a person is intoxicated with alcohol. If the content of alcohol in the blood is more than the prescribed limit, which usually varies from state to state or country to country, the driver is charged with a DUI offense. Now, when it comes to BAC calculation, it is usually measured in the form of percentage. For example, if the BAC of a person is 0.10 then it means that 0.10 percent (i.e. one-tenth of 1 percent) of his/her blood (either volume or mass) is alcohol.

BAC (by volume) level of 0.010 to 0.029 is considered is quite normal and harmless. If the BAC level is in between 0.030 and 0.059, it can affect your concentration, and in such situation it is highly advisable not to drive. If the BAC level is from 0.06 to 0.09, it can lead to temporary impairments like reasoning, glare recovery, peripheral vision and depth perception. In such situation, it would be a sin to drive any vehicle.


DUI or Legal BAC Limit

Every state or country sets a limit to the BAC level in order to maintain law enforcement and keep accidents at bay. The DUI limit of legal BAC limit completely depends upon every individual state or country. Every state or country set their own rules in this regard. For instance, 0.08 BAC is the prescribed limit in the entire United States. Even BAC Miami is 0.08. So, if you are driving on the roads of California, make sure your BAC is within the prescribed limit. On the other hand, there are some regions in the world that show zero tolerance to DWI, such as Australia, Brazil, Pakistan, Saudi Arabia, etc.

BAC Test or Sobriety Tests

These two tests are conducted in order to figure out the level of alcohol in the blood of any person. While BAC alcohol calculator provides direct result of the alcohol level, sobriety tests can be carried out to check whether the driver is driving with intoxication. Sobriety tests can also help officers to get a rough idea about the BAC level. Sobriety tests are of three types, and they are:

  1. Horizontal Gaze Nystagmus (HGN)
  2. Walk and Turn (WAT)
  3. One Leg Stand


Units of measurement

BAC can be defined is different ways, such as mass (alcohol)/volume (blood) and mass (alcohol)/mass (blood). In the United States, BAC is measured as 1% W/V, 1 gram alcohol per 100 ml of blood. So, 0.05 BAC means 50 milligrams of alcohol in 100 ml of blood.

BAC Formula

BAC can be calculated using the Widmark’s basic formula:

Percentage BAC = (A x 5.14/W x r) – 0.015 x H

What does these means.
‘A’ is total amount of alcohol consumed in ounces;
‘W’ is the person’s weight;
‘r’ is for alcohol distribution ratio;
‘H’ is the time period (in hours), right from the beginning of drinking till the calculation is made.

In this way, BAC for determining Driving under the influence offense is calculated and used for DUI process.