Blood Alcohol Content (BAC) Calculator
Easily estimate your Blood Alcohol Content (BAC) and track when the alochol has fully left your body.
* This tool is for educational purposes only and should not be used as a substitute for professional medical advice.
Approximate blood alcohol content: 0.197%
It would take approximately 14 hours to return to 0% BAC.
What is Blood Alcohol Content?
Blood Alcohol Content, or BAC, is the scientific measure of alcohol concentration in the blood. It is expressed as a percentage, which indicates the number of grams of alcohol present in 100 milliliters of blood. For example, a BAC of 0.08 percent indicates 0.08 grams of alcohol in every 100 milliliters of blood. This is important because it provides a good approximation of how intoxicated an individual is after consuming alcohol. The greater the BAC, the more intoxicated a person is.
BAC is widely used in medical and legal contexts. A BAC of 0.08 percent is the legal driving limit for adults in most countries, including the U.S., though intoxication begins at much lower levels. Because alcohol affects people differently depending on such variables as body weight, sex, and metabolism, BAC is a more accurate gauge of intoxication than a drink count.
How Do You Calculate Blood Alcohol Content?
BAC can be estimated mathematically using the Widmark Equation, which is the most commonly applied formula in alcohol research. The equation is written as:
BAC = (Dose in grams ÷ (Body weight in grams × r)) × 100 – (β × time)
Here, Dose in grams is the amount of pure alcohol consumed, r is the alcohol distribution ratio (0.68 for men and 0.55 for women), and β is the average metabolism rate. In most estimates, β is taken as 0.015 BAC per hour. This formula is helpful beacuse it takes in factors such as body size, biological sex, and the passage of time.
However, while this calculation provides a useful estimate, it is not perfect. For example, drinking on an empty stomach leads to faster absorption and a higher BAC peak than drinking after a meal. Because of these variables, online BAC calculators should only be used for general educational purposes. For a precise measurement, a breathalyzer, blood test, or urine test is required.
How Long Does Alcohol Stay in Your System?
The body breaks down alcohol at a fairly steady rate, but the exact time to eliminate alcohol from the system depends on many individual factors. The liver, on average, can metabolize the equivalent of one standard drink per hour, which translates to a reduction in BAC of about 0.015 percent per hour. This is the stand metabolism rate that we used for our tool.
However, this rate is extremely variable. An individual's body weight, age, sex, and liver health can all impact how fast the alcohol is broken down. Drinking on an empty stomach will also increase both the peak BAC and the duration of alcohol in the body. You must also remember that there are no shortcuts to sobriety. Coffee, energy drinks, cold showers, or exercise may make one feel more alert, but they will not speed up the liver's activity to burn off the alcohol. Time is the only element that will always lower BAC and eliminate alcohol from your bloodstream. Because of this, it is important to never attempt to drive or operate equipment until enough time has passed for your BAC to return to zero.