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Blood Alcohol (BAC) Calculator

Estimate your Blood Alcohol Concentration level.

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About Blood Alcohol Concentration (BAC)

Blood Alcohol Concentration (BAC) is a measurement of the percentage of alcohol in a person's bloodstream. A BAC of 0.10% means that 0.1% of a person's blood, by volume, is alcohol. This calculator provides an estimate of your BAC based on the Widmark formula, but it is not a legal document and should not be used to determine if you are fit to drive. Individual BAC levels can vary based on metabolism, medications, and food intake.

Factors that Influence BAC

  • Body Weight: A lighter person will have a higher BAC than a heavier person given the same amount of alcohol.
  • Gender: Women generally have a higher BAC than men after drinking the same amount of alcohol, due to differences in body composition and enzymes.
  • Time: The body metabolizes alcohol over time. The longer you wait after drinking, the lower your BAC will be.
  • Food: Eating food before or while drinking can slow the absorption of alcohol, resulting in a lower peak BAC.

Source: National Institute on Alcohol Abuse and Alcoholism (NIAAA). (n.d.). Understanding the Dangers of Alcohol Overdose. Read the article on NIAAA.NIH.gov.

Frequently Asked Questions

Is this BAC calculator legally accurate?

No. This calculator provides an estimate for informational and educational purposes only. It is not a legal tool and cannot be used to determine if you are fit to drive. Individual BAC can be affected by many factors, including metabolism, medications, and recent food intake. The only way to know your true BAC is with a calibrated breathalyzer or blood test.

What is the legal BAC limit for driving?

In all 50 U.S. states, the legal limit for drivers aged 21 and over is 0.08%. For commercial drivers, the limit is 0.04%. For drivers under 21, most states have 'Zero Tolerance' laws, where any detectable amount of alcohol (typically 0.01% or 0.02%) is illegal.

How long does it take for alcohol to leave your system?

On average, the body metabolizes alcohol at a rate of about 0.015% per hour. This means that if your BAC is 0.08%, it would take over 5 hours for it to return to zero. Nothing can speed up this process; coffee, cold showers, or food will not make you sober up faster.