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Blood Alcohol Content Estimator

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Everything runs locally in your browser — nothing is uploaded

Output

Estimate blood alcohol content with the Widmark formula: from the drink, its strength, your weight and sex it computes a peak BAC, then the current figure at an elimination rate of 0.015% per hour and the hours back to zero. ⚠️ This is an estimate with huge individual variation and must not be used to decide whether you can drive; “back to zero” is only a linear extrapolation — both statements are rows in the results. Everything runs in your browser; nothing you enter leaves this device.

Features

  • Widmark: grams of alcohol ÷ (body weight in grams × r), 0.68 male / 0.55 female
  • Ethanol density of 0.789 g/ml (not 1)
  • Peak BAC, current estimate and hours back to zero
  • Beer, wine and spirits presets, or custom ml and ABV
  • Number of drinks and hours since the first one
  • Weight in kg or lb
  • A prominent “must not be used to decide on driving” row
  • Computed locally; nothing is uploaded

How to use

  1. Pick a drink, or choose custom and enter ml and ABV
  2. Enter how many drinks and how long since the first
  3. Enter weight and sex (kg or lb)
  4. Results appear at once: peak, current level and hours to zero

FAQ

Can this tell me whether I can drive?
No, and that is the most important point. The same weight and the same drinks can differ twofold between an empty and a full stomach, and liver function, enzyme activity, medication and fatigue all matter. If you are driving, do not drink — do not gamble on this number.
Why 0.789 rather than treating ml as grams?
Because ethanol has a density of 0.789 g/ml. Treating 1 ml as 1 g overstates the alcohol by about 27% and pushes the BAC up. The density factor has to be applied.
Is “back to zero” accurate?
It is a linear extrapolation: peak divided by 0.015% per hour. Real metabolism varies between people and is not a straight line (metabolism may run a little faster at higher concentrations). Treat the time as a rough guide, not a guarantee.
Why is BAC higher for women on the same drinks?
The Widmark factor r is 0.55 for women and 0.68 for men, because body water differs: alcohol dissolves in water, and at the same weight women have less body water, so the concentration is higher. These are population averages with wide individual variation.

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