BAC Calculator
Estimate blood alcohol content based on drinks and weight.
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How This BAC Calculator Works
This calculator uses established scientific formulas validated in peer-reviewed literature. All calculations run locally in your browser — no data is sent to any server.
BAC Impairment Levels
| BAC % | Effects | Legal Status |
|---|---|---|
| 0.02 | Relaxation, slight warmth | Legal |
| 0.05 | Lowered inhibitions, impaired judgment | Legal |
| 0.08 | Impaired coordination, reaction time | ILLEGAL (all states) |
| 0.15 | Major balance/speech impairment | Aggravated DUI |
| 0.30+ | Loss of consciousness, life-threatening | Medical emergency |
Alcohol has 7 cal/gram — factor into your daily calories and TDEE.
How Your Body Processes Alcohol
After consuming alcohol, it is absorbed primarily through the small intestine (70-80%) and stomach (20%). The liver metabolizes alcohol at a nearly constant rate of approximately 0.015% BAC per hour through the enzyme alcohol dehydrogenase (ADH). This rate is largely fixed — coffee, cold showers, and exercise do not speed it up. The only thing that lowers BAC is time.
Gender differences are significant. Women typically achieve higher BAC than men after consuming the same amount of alcohol per kilogram of body weight. This is because women have less body water (52% vs 61%) and less gastric ADH activity, resulting in more alcohol entering the bloodstream. Hormonal fluctuations during the menstrual cycle can also affect alcohol metabolism.
Health Effects Beyond Impairment
Regular alcohol consumption affects body composition and fitness goals in several ways. Alcohol provides 7 calories per gram (nearly as much as fat at 9 cal/g), but these are "empty calories" with no nutritional value. Heavy drinking suppresses muscle protein synthesis by up to 37% (even with adequate protein intake), reduces testosterone, impairs sleep quality (particularly REM sleep), and increases cortisol — promoting visceral fat storage around the abdomen (check your risk with the Waist-to-Hip Ratio Calculator).
If alcohol is part of your lifestyle, factor its calories into your daily intake targets and TDEE. A standard drink contains approximately 14g of alcohol (98 calories just from the alcohol, before mixers). Use the Macro Calculator to adjust your food intake on drinking days.
Frequently Asked Questions
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