Blood Alcohol Level Calculator is designed to estimate the level of alcohol intoxication in human’s blood for legal or medical purposes. The blood alcohol concentration (or blood alcohol content, BAC) is expressed in grams per 100 ml of blood and is denoted as a percentage. To calculate your blood alcohol level just fill in the appropriate fields of the calculator and click the ‘Calculate’ button. You can independently choose measurement units for your body weight and the volume of alcoholic beverages drunk. Using the beverage dropdown field, you can choose the beverage drunk. In case the alcohol percentage popping up automatically differs from the one of the beverage drunk you can correct it manually. In case more then one beverage was drunk you can click the “+” symbol on the right hand side to get additional fields. You can also click the “–” symbol to delete the redundant lines. Along with the obtained blood alcohol content value, a graph of its dependence on time is also displayed. The calculated BAC value is denoted by red dot. The intersection point of the graph with the time axis gives the time assessment when BAC = 0%.
What is BAC ?
Blood Alcohol Content (BAC) is a measurement of a person’s blood alcohol concentration expressed as a percentage of alcohol per volume of blood (grams per 100 ml).
The total amount of alcohol absorbed into a person’s bloodstream depends on the amount of alcohol consumed, the person’s body mass (or weight), and the proportion of the consumed alcohol that remains in the person’s blood. The last factor depends, among other things, on a person’s gender.
The blood alcohol content decreases over time as a result of the elimination of alcohol from the bloodstream. The rate at which alcohol is absorbed and eliminated from the body vary from person to person, and even for the same person over time. Therefore, an accurate calculation of the BAC is not possible and empirical formulas are used instead for blood alcohol level estimation.
The most popular formula commonly used in blood alcohol content calculators is the Widmark’s formula. The simplified form of this formula, that we use in our online BAC calculator, can be expressed as follows:
$$BAC(\%)=\frac { 5.14\cdot A }{ r\cdot W } -0.015\cdot H,$$
where \(A\) is the volume of alcohol consumed (in liquid ounces), \(W\) is a person’s weight (in pounds), \(r\) is the gender related constant of alcohol distribution (0.73 for men and 0.66 for women), \(H\) is the hours elapsed since first drink.
Most often, the need to assess the level of the blood alcohol level arises when it is necessary to get behind the wheel of a car after drinking alcohol. The legal limits for BAC when driving vary from country to country and can be found on the WHO website. The graph of the BAC dependence on time can be used to assess the time when the BAC will reach a desired level.
It’s important to emphasize that our BAC calculator gives blood alcohol concentration estimates based on gender, weight, alcohol percentages and time frames. This is not legal advice on BAC percentages. There are many variables that can also affect these percentages like medications you may be taking, individual metabolism rates, what you ate before you started to drink. There are many other factors that can affect blood alcohol level, which is why this is a tool that can be used for educational purposes only.
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Disclaimer. Please remember that this calculator is intended for education use only. It is not intended to replace the medical advice of your doctor or healthcare provider. Please consult your doctor for advice about your specific medical condition.