BAC Calculator – Measure Blood Alcohol Concentration & How Long To Be Alcohol-Free

blood alcohol calculator

Our BAC calculator is newly released and digitally designed for determining both blood alcohol concentration as well as how long alcohol might stay in your system.

Blood alcohol concentration is defined in terms of the weight of ethanol (Ethyl alcohol) in a volume of blood or breath. In the United States the typical measure is “grams of ethanol in 100 milliliters of blood” or in 210 liters of breath. BAC is typically reported as a percentage such 0.10 or 0.245. It is also referred to as blood alcohol content and blood alcohol level.

BAC Calculator

This unit quickly computes approximately what the Blood Alcohol Concentration might be at the end of a drinking session. It also estimates the time it could take to metabolize that level to zero.  The answers should not be taken as absolute, as every person is different.

How It Works

Click on the graphic image icon and fill-in these questions:

  • Gender
  • Weight
  • Number of Drinks
  • Hours Spent Drinking

Then click the “calculate” button and that’s it, fast and easy. The results will be displayed as the estimated BAC at the end of drinking and the estimated time when it might go down to 0.0000.


Don’t Drink & Drive

Even a small amount of alcohol can impair the judgement, timing and coordination of someone’s ability to operate a motor vehicle.

The Formula

The formula used is a procedure provided courtesy of Herbert Moskowitz, Ph.D., a noted alcohol researcher. These calculations are based on the National Safety Board, Department of Transportation’s formulation.

Time Spent Drinking

Once the BAC is computed based on the above variables, the percentage of alcohol metabolized during drinking time is subtracted. (note: this formula uses what is considered a conservative basis of .012 per hour decline in the level of alcohol in the body).

Other Related Elements and Factors

There are other aspects; age, tolerance and physical fitness. These variabilities could produce a small fraction of error in the final answer. Here is how they might affect the outcome of our formulation.

Age: Younger people have a higher proportion of body water as a fraction of their total weight, and older people have less. So, a younger person may potentially have a lower BAC than an older person.

Physical Fitness: Individuals who may be overweight may have a smaller proportion of their body weight as water.  Lean people tend to have a larger fraction of their body weight as water. Therefore, overweight people could have a higher BAC than our formula indicates.

Tolerance: A person who is a regular drinker, will have higher tolerance for metabolizing alcohol than someone who is not.