Blood Alcohol Calculator
Estimate your blood alcohol content and alcohol elimination time after drinking.
About This Tool
The Alcohol Calculator estimates your Blood Alcohol Concentration (BAC) based on the amount of alcohol consumed, your body weight, sex, and elapsed time since drinking. It helps you understand the approximate effects of alcohol on your body and the estimated time to return to sobriety.
This calculator provides estimates for educational purposes only. Individual results vary significantly. Never use this to determine if you are safe to drive. When in doubt, do not drive.
How to Use
- Select your gender and enter your body weight in kilograms.
- Add each type of drink you consumed with the amount.
- Enter how long you were drinking and how much time has passed since your first drink.
- Click Calculate to see your estimated BAC and sober-up time.
- Remember: this is only an estimate. Never drive if you have been drinking.
Frequently Asked Questions
What is BAC (Blood Alcohol Content)?
BAC measures the percentage of alcohol in your bloodstream. In Korea, the legal limit for driving is 0.03%. At 0.08%, penalties become significantly more severe. BAC depends on your weight, gender, amount consumed, and time elapsed.
How is BAC calculated?
This calculator uses the Widmark formula: BAC = (Alcohol in grams × 0.7894) ÷ (Body weight × Gender constant) − (Hours × 0.015). The gender constant is 0.68 for males and 0.55 for females.
How long does it take for alcohol to leave your system?
The body eliminates alcohol at roughly 0.015% BAC per hour. One standard drink (soju 1 shot, beer 1 glass) takes about 1-2 hours to process. A full bottle of soju can take 8-10+ hours to fully eliminate.
What are the drunk driving penalties in Korea?
BAC 0.03-0.08%: license suspension, fine up to 5 million won. BAC 0.08%+: license revocation, 1-5 years prison or 5-20 million won fine. Repeat offenders face harsher penalties. Refusing a breathalyzer test results in automatic license revocation.
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How It's Calculated
BAC is estimated using the Widmark formula: BAC = [alcohol consumed (g) ÷ (body weight (g) × Widmark factor r)] × 100 − (elimination rate × hours since drinking).
The Widmark factor (r) accounts for body water distribution: approximately 0.68 for men and 0.55 for women, reflecting differences in average body composition. Alcohol consumed in grams is derived from the volume of each drink, its alcohol percentage, and the density of ethanol (0.789 g/mL).
The elimination rate represents how quickly the liver metabolizes alcohol, averaging 0.015 g/100mL per hour (range: 0.010–0.020). This means BAC drops by roughly 0.015% per hour regardless of the amount consumed.
Legal BAC limits vary by country: 0.08% in the US/UK, 0.05% in most of Europe and Australia, and 0.03% in South Korea. Even below legal limits, alcohol impairs reaction time and judgment.
⚠️ Disclaimer
BAC estimates are approximate and vary based on individual metabolism, food intake, medications, and other factors. Never use this tool to determine whether you are safe to drive. If you have consumed alcohol, always arrange a safe ride home. This tool does not constitute legal or medical advice.