How do I use the Blood Alcohol Calculator (BAC)?

Select your gender and enter your body weight. Enter the number of drinks consumed. Choose the drink type (beer, wine, spirits) or enter custom size and ABV. Enter hours since your first drink. Click Calculate BAC to see your estimated blood alcohol content.

Is the Blood Alcohol Calculator (BAC) free?

Yes, the Blood Alcohol Calculator (BAC) is completely free. It runs entirely in your browser with no signup, no download, and no data sent to any server.

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Blood Alcohol Calculator (BAC)

Estimate your blood alcohol content using the Widmark formula based on drinks, weight, gender, and time.

blood alcohol calculatorBAC calculatorblood alcohol contentWidmark formula

Blood Alcohol Calculator (BAC)

Gender

Body Weight

Number of Drinks

Drink Type

Hours Since First Drink

How to use

How to Use the Blood Alcohol Calculator

1 Select your gender and enter your body weight.
2 Enter the number of drinks consumed.
3 Choose the drink type (beer, wine, spirits) or enter custom size and ABV.
4 Enter hours since your first drink.
5 Click Calculate BAC to see your estimated blood alcohol content.

The Blood Alcohol Calculator uses the Widmark formula, the standard method for estimating BAC. It accounts for gender differences in body water distribution (males have a higher water ratio at 0.68 vs 0.55 for females). The body metabolizes alcohol at approximately 0.015% per hour, which is subtracted based on elapsed time.

In the United States, 0.08% BAC is the legal limit for driving. However, impairment begins at much lower levels — reaction time and judgment are affected at just 0.02%. This calculator provides estimates only. Actual BAC varies based on metabolism, food consumption, medications, and individual physiology. Never drink and drive.

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