Calculate Your BAC

What is BAC?


(Beer ~ 12 oz. Wine Glass ~ 4 oz. 1 Shot ~ 1.5 oz)



(Beer ~ 4-4.5% Wine ~ 15-20% 1 Shot ~ 30-50%)


All 50 states, including the District of Columbia, have now set the legal limit of Blood Alcohol Concentration (BAC) at .08% for DUI & DWI offenses. For commercial drivers, the legal limit is .04% BAC.

There is no blood alcohol calculator that is 100% accurate because of the number of factors that come into play regarding the consumption and reduction (burnoff) rates of different people. Factors include the gender of the drinker, metabolism rates, various health issues, drinking tolerance and frequency, etc. This calculator provides a rough estimate of the BAC level based on known inputs. This calculation assumes a volume of .54 ounces of alcohol (one shot of distilled spirits, a glass of wine, or 12 ounces of beer).

DISCLAIMER: This calculator is by no means a guideline when making the life or death decision whether you can drink and still drive or avoid being arrested or worse! The best policy is don’t drink and drive. Period. The Law Office of Daryl B. Thompson assumes no responsibility for you using this calculator as the determining factor whether you should drive or not.


When you drink alcohol, the alcohol goes quickly from your mouth to your stomach, and then to your small intestine. Most of the alcohol is absorbed into the blood stream from the small intestine. As you continue to drink, more alcohol enters the blood stream, increasing the blood alcohol concentration (BAC).

After you have finished drinking (had your last drink!), alcohol will continue to be absorbed into the blood stream. It is not uncommon, after a person has had their last drink, they then get into their car to drive home. On the way home, they find themselves feeling the effects of the alcohol and becoming more impaired. This is the result of the continual rise of the BAC as your body is continuing to absorb alcohol through the small intestine. Alcohol as a general rule, will continue to be absorbed into your blood stream for up to one hour after your last drink.

Some people have a last drink, then sit around for an hour before they drive home, to help sober themselves up. WRONG! The hour you wait, after your last drink, you just get more intoxicated and increase your BAC. If you have had too much to drink, STOP DRINKING AND CALL A CAB. Waiting an hour will only make your BAC higher in most cases.

Another item to remember, that will have a direct affect on your BAC is to eat something. Remember, the alcohol goes through the stomach to the small intestine. Eating something delays the alcohol entering into the small intestine and thereby slowing down the absorption rate into the blood stream. Eating will not stop absorption, it will only slow it down.

Alcohol loves water. Alcohol has an affinity for water. Alcohol will distribute itself not throughout your entire body, but just in the water bearing tissues of your body. The higher the water bearing tissue or organ, the higher the blood alcohol concentration will be in that tissue or organ. For example, higher concentrations of alcohol can be found in the liver, blood, lungs, muscles, etc. Less water, and no alcohol concentration will be found in areas of bone, fat, cartilage, etc. Alcohol is readily absorbed into muscle and not into fat. Therefore, the better shape someone is in, the more alcohol will spread throughout the rest of the body and lower the overall blood concentration. While the heavier, more out of shape person, because of less muscle, will have a higher concentration of blood alcohol in their blood stream.

This should give you a little better insight into blood alcohol absorption and concentration. Other factors that come into play in determining your BAC, i.e., the number of drinks you have consumed, the amount of alcohol in each drink, the length of time you have been drinking (start and stop times), your weight, your gender, percentage of water bearing tissue, rate of absorption and rate of elimination. Understanding all of these factors will go to help you understand how BAC is determined.