BAC (Blood Alcohol Content) Calculator
Estimate blood alcohol content (BAC) based on drinks, weight, and time. For informational purposes only. BAC is affected by many factors (food, metabolism, medications, health, and measurement error), so this tool should be treated as a rough estimate only.
Inputs
Estimated BAC
Estimated BAC
0.0639
Alcohol (oz)2.4
Distribution factor (r)0.73
Time to 0.00 (hours)4.3
Uses a Widmark-style estimate with an average elimination rate of ~0.015 BAC/hour.
BAC varies widely by person, food intake, and measurement error.
How to use it
- Enter your body weight and select a distribution factor option.
- Add drinks (or total alcohol) and the time since drinking began.
- Review estimated BAC and a conservative time-to-sober estimate.
- If you’ve been drinking, do not drive—use a safe ride option.
Key formulas
- Widmark-style estimate (common form)
- BAC ≈ (A × 5.14 / (W × r)) − 0.015 × H
- A = ounces of alcohol, W = weight (lb), r = distribution ratio, H = hours since first drink.
FAQ
A standard drink contains about 0.6 fl oz of pure alcohol—commonly 12 oz beer (5% ABV), 5 oz wine (12% ABV), or 1.5 oz spirits (40% ABV).
It’s an estimate. BAC varies with food, metabolism, body composition, medications, health, and measurement error. Only a calibrated breath or blood test can measure BAC.
A common rule of thumb is that BAC decreases around 0.01–0.02 per hour, but the rate varies widely. Time is the primary factor.
No. Coffee, cold showers, and exercise may change how you feel, but they don’t reliably reduce BAC. Time is what lowers BAC.
Many US jurisdictions use 0.08% for standard adult driving, but laws vary by location, age, and license type. Always follow local laws and choose a safe ride if you’ve been drinking.
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Disclaimer
Estimate only. Do not use this tool to decide whether it’s safe or legal to drive or operate machinery.