Blood Alcohol Calculator

Region: United States standard drink: 14g/17.7ml alcohol.

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Next step: Understand your results

This tool provides a rough estimate of your BAC levels using a basic version of the Widmark Formula. To gain a better understanding about BAC dissipation rates, take a look at our alcohol metabolism guide which provides further information about how long alcohol stays in your system.

Alcohol Metabolism Info


This BAC calculator is for information purposes only. There are many variables that mean this tool cannot fully determine your BAC level, and therefore whether an individual is able to lawfully drive a vehicle. We strongly suggest that if you have any alcohol in your body: do not drive.

By using this tool, you acknowledge that any information presented may contain inaccuracies or errors and we expressly exclude liability for any such inaccuracies or errors to the fullest extent permitted by law.

This tool employs a basic version of the Widmark Formula, which can be found below. The variables used in the formula can be expressed as; A = liquid ounces of alcohol consumed, W = your weight in pounds, r = a gender constant (.73 for men and .66 for women) and H = hours since your first drink.

Widmark Formula

%BAC = (A x 5.14 / (W x r)) - .015 x H

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