AL DUI BAC Level Calculator Chart- How to Find Blood Alcohol Content

What is BAC? Find your Blood Alcohol Content by use of a BAC Calculator

Blood Alcohol Content (BAC) is the concentration of alcohol in a person’s blood. This BAC level is measured as mass per volume. For example, a BAC of 0.02% grams of alcohol per 100 grams of individual’s blood, or 0.02 grams of alcohol per 100 grams of blood. The grams are the “mass” as compared to the “volume” (100 grams) of blood.

This BAC number, for motorists who consume alcohol, is important in driving under the influence cases (DUI) since a relationship between a person’s legal limit alcohol has been statistically proven to correlate to the chances of a car accident. By using a BAC calculator, a person can make a fairly accurate estimate of his or her BAC by inputting gender, weight, time of drinking and number of standard drinks consumed.

Alcohol Driving Limit and Traffic Safety

The origin of the 0.08 DUI legal limit, in America, can be traced back to a 1964 NHTSA-funded study overseen by Professor Robert F. Borkenstein, of Indiana University. Borkenstein, an ex-police officer and inventor of the Breathalyzer, did not have formal training in the scientific method for statistical analysis or a working knowledge of “testing and measurement” science. So, the federally-funded National Highway Traffic Safety Administration study predictably exaggerated the seeming immediate jump in risk factors for all drivers at or above the 0.08 BAC.

Hence, subsequent statistical analysis of the Grand Rapids “curve” by Allsop in 1966 and by Hurst, Harte and Frith, in 1994 showed flaws in the numbers posted. Both studies concluded that the case/control comparisons used by Borkenstein in the 1964 Grand Rapids study were biased. “This curve indicates that accident risk increases with increased blood alcohol concentration regardless of self-reported drinking frequency.”

Additionally, a breakdown of driving skills for the subgroup of regular drinkers showed little additional accident risk for these drivers at the legal limit for alcohol, 0.08 grams percent, as compared to the accident risk from infrequent drinkers, at the same BAC levels. So, the important variable of a driver’s alcohol tolerance was not factored in by Borkenstein and his Grand Rapids team.  Source: https://www.ncbi.nlm.nih.gov/pubmed/7999209

How to Calculate BAC with a Blood Alcohol Calculator

People facing DWI-DUI charges want to know their BAC levels after a certain number of drinks. By using a blood alcohol level (BAL) chart, or an interactive BAL calculator, a person who drinks alcoholic beverages can estimate blood alcohol content, as compared to the legal limit of alcohol.

The easiest place to look for BAC calculators is the Internet. Over 100 sites have an alcohol content BAC calculator or BAC chart to allow a user to input data like weight, number of drinks, etc. Depending on the type of BAC chart used, either an interactive DUI calculator can be used, like the one below, or a static chart, with a grid showing how to calculate BAC.

DUI per se laws (DUI by being over the legal limit) in America take away the need for the Prosecutor to prove impairment and establish a numeric alcohol level for driving, For a drinking driver age 21 and over, that BAC level is 0.08 grams percent, as measured by a forensic breath alcohol test. Whenever using a BAC calculator, it is better to underestimate than to be too optimistic, when approximating being at the legal limit.


Weight: (pounds)
Drinks consumed:(12 oz. beer or equivalent)
Over time period: (hours)
Your BAC will be:

Using a BAC Calculator to find Your Estimated Blood Alcohol Content

The above blood alcohol calculator estimates the percentage of alcohol in the blood by number of drinks in relation to a drinker’s body weight. This percent is estimated by:

› Counting your drinks (1 drink equals 1 ounce of 100 – proof liquor, one five ounce glass of table wine or one 12 – ounce bottle of regular beer).

› Using the chart below and under number of “drinks” and opposite “body weight,” finding the percent of blood alcohol listed.

› Subtracting from this number the percent of alcohol “burned up” during the time elapsed since your first drink. This figure is .015% per hour. (Example: 180 lb. man – 8 drinks in 4 hours / .167% minus (.015×4) = .107 %.

FREE Lawyer Consultation for Alabama DUI

This page and the BAC calculator was created by Birmingham DUI attorney Whitney Polson. Mr. Polson hopes that this tool helps citizens estimate BAC levels, to improve driving safety in America.

Alabama attorney Polson, an Alabama drunk driving book co-author, and his father, Birmingham DUI lawyer Mark Polson, are known to be among the best DUI lawyers in Alabama! The lawyers in Alabama cover the State of Alabama, with their statewide criminal law practice, as DUI specialists.

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