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ARVENRA
Medical tools

BAC Calculator

An educational estimate of blood alcohol concentration using the Widmark equation.

This tool estimates blood alcohol concentration from the amount of alcohol consumed, body weight, sex and elapsed time.

The result carries no label such as legal or safe, and no legal threshold is shown anywhere. Limits differ between countries, impairment begins below every legal limit, and individual variation in absorption and elimination is far wider than this number implies.

Your details

The formulas use different coefficients for each sex.

Typical range: 30 – 300

Typical range: 0 – 50

If you know the exact amount, enter it instead of a drink count.

Typical range: 0 – 500

Typical range: 0 – 24

The WHO standard unit is 10 grams.

Typical range: 6 – 20

The values you enter are calculated in your browser only — nothing is stored or transmitted.

Fill in your details and press calculate — your result will appear here.

Formula and method

The Widmark equation with an average elimination rate of 0.015 percent per hour. A standard drink defaults to 10 grams of pure alcohol.

Formula used

Widmark equation with 0.015 %/h elimination

Assumptions and limits

  • Real elimination rates vary between individuals from roughly 0.010 to 0.025 percent per hour.
  • Food, medication and health conditions all affect absorption and are not accounted for here.

Scientific sources

  1. Widmark EMP. Die theoretischen Grundlagen und die praktische Verwendbarkeit der gerichtlich-medizinischen Alkoholbestimmung. Urban & Schwarzenberg, Berlin, 1932.

  2. National Highway Traffic Safety Administration. Computing a BAC Estimate. U.S. Department of Transportation, Washington DC.

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