Alcohol Concentration Worksheet

This worksheet is one element of a set of guidelines for making low-risk decisions about the use and non-use of alcohol. For more information see this section of the Minnesota Drivers Manual. If you would like to purchase our booklet Alcohol: Choices and Guidelines for College Students, please call the Minnesota Institute of Public Health at 800-782-1878.

To estimate your own personal limit to avoid future problems related to a drinking and driving violation, you can use the following steps to calculate the maximum number of drinks you can have at any time.

Remember, in order for this limit to be helpful, you must decide what is low risk drinking before you begin drinking. Research has shown clearly that a person who has started to drink will underestimate his/her AC level.

Step 1 Determine your weight __________.

Step 2 Using the appropriate AC Chart below, find the column that is closest to your weight. If your weight is between two columns, use the lower weight column to insure that your calculations will be within limits that are legal and low risk.

Step 3 Read down the column you located in Step 2 that is closest to your weight until you find an AC level of .04. This is the highest AC level you can reach without showing significant impairment of body functions and skills that affect your driving.

Step 4 To calculate your AC level subtract the time factor (see Time Factor Table) from the figure on the chart to obtain the approximate AC. For example, for a 160 lb. man who has had 4 drinks in two hours, take the figure .09 (from the chart for males) and subtract .03 (from the Time Factor Table) to obtain an AC of .06%.

Body Weight: Calculations are for people with a normal body weight for their height, free of drugs or other affecting medication and neither unusually thin or obese. There are two ways to ensure that your AC level does not impair your ability to drive: (1) pace your drinks at a rate that never results in a cumulative AC level of .04 or greater or (2) allow enough time after drinking for the body to eliminate enough alcohol so that the AC level remaining is less than .04 before you drive.

If you choose to drink alcohol, the only low risk method is to pace your drinks so you never reach an AC level which will impair your driving. As stated earlier, judgment is one of the first areas impaired by alcohol and once you have exceeded a .04 AC level it becomes increasingly difficult to accurately assess your level of impairment.

If you drink enough alcohol to go beyond an AC level of .04, the best thing to do is not to drive and find another person to drive you or call a cab. If neither of those options is available, the Time Factor Table below will help you determine when enough alcohol will have been eliminated from your body to reduce your AC level to below .04.

This is extremely important because it is possible for a person who has consumed a large amount of alcohol to stop drinking late at night, sleep for several hours and still have an AC level high enough to significantly impair their driving the next morning.

Step 5 Now calculate the maximum number of drinks you can have without reaching an AC level of .04 in

1. Hour ____________
2. Hours ____________
3. Hours ____________
4. Hours ____________
5. Hours ____________

NOTE: Be sure to substract .015 for each hour after drinking including the first.