BAC Calculator accuracy and testing

Formula source

• This calculator uses the **Widmark Formula**: `BAC = [Alcohol(g) / (Body Weight(g) × r)] × 100 - (0.015 × Hours)` * **r (distribution ratio):** 0.68 for men, 0.55 for women. * **Metabolism:** Assumes body eliminates alcohol at 0.015% per hour.

Test cases

Known limitations

• Strictly an estimate. Actual BAC depends on genetics, body composition, food intake, and medications. **Do not use this tool to decide if you can drive.**

Assumptions

• Each standard drink is treated as about 14 grams of pure alcohol.
• The estimate uses fixed body-water distribution ratios by sex and a typical elimination rate of 0.015% BAC per hour.
• Real BAC can vary significantly based on food intake, medications, metabolism, and drink strength.

Unit handling

• Gender accepts one of the configured options.
• Body Weight accepts values in lbs.
• Standard Drinks accepts numeric values.
• Hours Since First Drink accepts numeric values.
• Estimated BAC is displayed as a percentage.

Rounding rules

• Number displays use up to 2 decimal places in the calculator UI.
• Percent outputs are displayed with two decimal places.

Version history

Change log