Blood Alcohol Content Calculation


Blood Alcohol Estimation

The following table will allow you to estimate your blood alcohol content (BAC), based upon the number of drinks you have consumed over a specified period of time.

For the sake of simplicity, the table works on the assumption that you have consumed drinks with a consistent level of alcohol. If you have consumed stronger drinks, or are not certain how much alcohol was in the drinks you consumed, you will need to take that into consideration when using the table and estimate based on a higher number of drinks than you actually consumed.

The chart also assumes that your consumption has been consistent over a two hour period, meaning that you consumed the drinks slowly over the entire period, and did not consume most of the alcohol over a shorter period of time within the two hour window. Also, the table assumes that you were sober (BAC of 0.00) at the start of the two hour period. The table takes body mass into consideration but does not take gender differences into consideration, and your BAC may be affected by your gender even when you control for weight and amount of alcohol consumed -- women tend to become intoxicated more quickly than men. Blood alcohol levels may also be affected by food you have consumed, other beverages consumed, your level of physical fitness, your metabolism, medications you take, as well as other factors. This table is not a substitute for an actual blood alcohol test.

While the table may provide a decent estimate of your blood alcohol content, please do not rely upon the resulting figure to determine if it is safe or legal to drive a car. If you have consumed enough alcohol to be concerned about driving, whatever your blood alcohol content may be, you should find alternate transportation.

For purposes of this chart, one drink is approximately 1.5 ounces of liquor, (40% alcohol), approximately 5 ounces of wine (12% alcohol), or approximately 12 ounces of beer (5% alcohol).

Your Weight Number of Drinks
Over a Two Hour Period
99-109 1 2 3 4 5 6 7 8
110-129 1 2 3 4 5 6 7 8
130-149 1 2 3 4 5 6 7 8
150-169 1 2 3 4 5 6 7 8
170-189 1 2 3 4 5 6 7 8
190-209 1 2 3 4 5 6 7 8
210 - 229 1 2 3 4 5 6 7 8
230 and up 1 2 3 4 5 6 7 8
Yellow: BAC of .05 or Higher
Orange: BAC of .08 or Higher
Please note that results will vary by gender.

Effects of Blood Alcohol

Although an individual's alcohol tolerance will influence how alcohol effects their abilities and coordination, as a general pattern blood alcohol levels can be associated with symptoms as follows:

  • BAC .02 - A typical drinker will begin to feel the effects of alcohol consumption.

  • BAC .04 - A typical drinker will start to feel relaxed, and will become more sociable and talkative.

  • BAC .05 - A drinker's judgment, attention and coordination will show signs of impairment, and the drinker will experienced reduced judgment and decision-making ability.

  • BAC .08 - A drinker will show signs of impaired coordination and a marked decline in driving ability.

  • BAC .10 - A drinker's reaction time and physical coordination will show clear impairment.

  • BAC .12-.14 - A typical drinker will become drowsy, and may show emotional instability. Judgment, perception, coordination, balance, reaction time and comprehension are significantly impaired. Vision impairment occurs, particularly in perception of detail, recovery from glare, and peripheral vision. Vomiting may occur.

  • BAC .18-.25 - A drinker will become disoriented, lethargic, dizzy and confused, and is likely to be staggering and have slurred speech. Muscle coordination is markedly impaired, and some drinkers will be unable to walk. The drinker is likely to be emotionally unstable. Vision impairments expand to include impaired perception of color, dimension, motion, shapes and forms.

  • BAC .25-.30 - A drinker will display severe loss of motor function and general inertia, and may become unresponsive to outside stimulation. Drinkers will often be unable to stand or walk, and are likely to vomit or become incontinent. Some drinkers will become insensible or lose consciousness.

  • BAC .30-.50 - Most drinkers will be unconscious, and will have depressed or absent reflexes, with impaired circulation and respiration. At this level of impairment a drinker will likely have a reduced body temperature and become incontinent.

A serious medical emergency exists at a BAC of .37 or higher, with a possibility of death. For most people, a BAC of .45 or higher will be fatal. Please recall that some drinkers have below-average tolerance of alcohol and may experience symptoms of severe intoxication or life-threatening symptoms at a significantly lower alcohol level.

Do Not Drink and Drive

Remember - when in doubt about possible impairment or intoxication, don't drive. If your driving skills are impaired as a result of the consumption of alcohol, some jurisdictions will prosecute you for drunk driving even if your blood alcohol content is below the legal limit. You also may potentially be convicted of drunk or impaired driving based upon chemical test results even if you believe you are not impaired in your ability to drive.

Copyright © 2004 Aaron Larson, All rights reserved. No portion of this article may be reproduced without the express written permission of the copyright holder. If you use a quotation, excerpt or paraphrase of this article, except as otherwise authorized in writing by the author of the article you must cite this article as a source for your work and include a link back to the original article from any online materials that incorporate or are derived from the content of this article.

This article was first published on Mar 1, 2004, and was last reviewed or amended on May 26, 2016.