Free Blood Alcohol Content Calculator

Estimate your blood alcohol content (BAC) using the Widmark formula based on drinks consumed, body weight, and time.

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drinks

1 standard drink = 12 oz beer, 5 oz wine, 1.5 oz liquor

lbs
hours

Estimated BAC

0.040 %

Hours Until BAC = 02.7 hours

Estimated BAC vs Standard Drinks

View formula & how it works →

Widmark Formula for BAC

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

Where:

  • 1 standard drink = 14 grams of alcohol
  • r = 0.73 for males, 0.66 for females (body water ratio)
  • 0.015 = average BAC reduction per hour

    • Legal Limits

    BACStatus 0.00%Sober 0.02-0.04%Mild effects 0.05-0.07%Impaired 0.08%+Legally intoxicated (most US states)

    Example Calculation

    A 180 lb male who had 3 drinks over 2 hours.

    1. 01Alcohol = 3 x 14 = 42 grams
    2. 02Weight = 180 x 453.6 = 81,648 grams
    3. 03BAC = (42 / (81,648 x 0.73)) x 100 - 0.015 x 2
    4. 04= 0.0705 x 100 - 0.030 = 0.041%

    Frequently Asked Questions

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