BAC Calculator

A Blood Alcohol Content (BAC) calculator estimates your current blood alcohol level based on your gender, weight, number of drinks, and drinking duration. BAC is expressed as a percentage of alcohol in your bloodstream — for example, a BAC of 0.08% means 0.08 grams of alcohol per 100 milliliters of blood.

This calculator uses the Widmark formula, which is the most widely-used method for estimating BAC. It accounts for gender differences in body water content (men have a higher water ratio) and the body's natural metabolism of alcohol at approximately 0.015% per hour.

Understanding your estimated BAC can help you make informed decisions about drinking. In most US states, the legal driving limit is 0.08%. However, impairment can begin at much lower levels. This calculator is for educational purposes only — actual BAC depends on many individual factors.

1. Select your gender — Male or Female (affects the Widmark factor).
2. Choose your unit system — Imperial (lbs) or Metric (kg).
3. Enter your weight — Your current body weight.
4. Enter standard drinks consumed — 1 standard drink = 14g of pure alcohol.
5. Enter alcohol percentage — The ABV of your beverage (default 5% for beer).
6. Enter drinking duration — How many hours you've been drinking.
7. Review your estimated BAC — See your level, status, and time until sober.

Widmark Formula:

BAC = (Alcohol in grams / (Body weight in grams × r)) × 100 - (0.015 × hours)

Where r = 0.68 for males, 0.55 for females

1 standard drink = 14 grams of pure alcohol

Metabolism rate: approximately 0.015% BAC per hour

Time until sober = BAC / 0.015 hours