BAC Calculator: Estimate Your Blood Alcohol Content
Estimate your blood alcohol concentration (BAC) based on the number of drinks, your body weight, biological sex, and time elapsed. This is an educational estimate, not a measure of whether it is safe to drive.
Enter your weight and number of drinks to estimate your BAC.
What Counts as a Standard Drink?
12 oz Beer
5% ABV = 1 standard drink
5 oz Wine
12% ABV = 1 standard drink
1.5 oz Shot
40% liquor = 1 standard drink
How BAC Is Calculated
Blood alcohol content (BAC), also called blood alcohol concentration, measures the amount of alcohol in your bloodstream as a percentage. A BAC of 0.08% means there are 0.08 grams of alcohol per 100 milliliters of blood. This calculator estimates BAC using the Widmark formula, the most widely used method for predicting blood alcohol levels:
The Widmark factor accounts for body water content: approximately 0.73 for men and 0.66 for women, since women typically have a higher percentage of body fat and less water to dilute alcohol. The body metabolizes alcohol at an average elimination rate of 0.015% per hour, which is why BAC falls over time.
Factors That Affect BAC
- Number of standard drinks: More alcohol consumed means a higher BAC.
- Body weight: A larger body has more blood volume to dilute alcohol, lowering BAC.
- Biological sex: Women generally reach a higher BAC than men of the same weight.
- Time elapsed: The liver removes about one standard drink per hour.
- Food intake: Drinking on an empty stomach causes faster alcohol absorption.
- Drink strength: Craft beers, large pours, and mixed drinks often exceed one standard drink.
- Metabolism, medication, fatigue, and health: These can raise or lower your actual BAC.
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Frequently Asked Questions
This calculator uses the Widmark formula, the standard method for estimating BAC. It factors in the number of standard drinks, your body weight, biological sex, and the time elapsed since you started drinking. The body eliminates alcohol at an average rate of about 0.015% per hour.
Disclaimer: This BAC calculator is for educational purposes only and provides an estimate based on the Widmark formula. Actual BAC varies widely based on metabolism, food intake, medication, health, and other factors. A breathalyzer or blood test is the only accurate measure. Never use this tool to decide whether you are safe to drive. If you have been arrested for DUI or DWI, contact a licensed attorney immediately.