BAC Calculator
Estimate your blood alcohol level based on drinks, weight, and time. Includes legal limits for 48 countries.
⚠️ This is an estimate only with ~20% uncertainty. Never use this tool to decide if you are safe to drive. Always use a certified breathalyzer for legal decisions.
How to Use
- 1 Enter your body weight and select kg or lbs
- 2 Select your biological sex (affects alcohol metabolism)
- 3 Add drinks you have consumed — choose from presets or enter custom values
- 4 Set how many hours since your first drink
- 5 Select your country to see the legal driving limit
- 6 View your estimated BAC, impairment level, and time to sober
What You Get
Blood alcohol content (BAC) estimator using the Widmark formula. 13 drink presets, 48 country legal limits, 8 impairment categories, time-to-sober projection, and visual BAC scale.
Input: 180 lbs male, 2 beers (330ml), 1 hour ago
Output: BAC ~0.029% — Minimal impairment
Input: 130 lbs female, 3 wine glasses, 2 hours ago
Output: BAC ~0.079% — Moderate impairment
Input: 200 lbs male, 1 shot, 0 hours ago
Output: BAC ~0.019% — Minimal impairment
Input: 150 lbs female, 4 cocktails, 1 hour ago
Output: BAC ~0.196% — Severe impairment, dangerous
How do I calculate my blood alcohol level?
Enter your body weight, biological sex, the drinks you consumed (type, volume, alcohol percentage, and quantity), and how many hours since your first drink. The calculator uses the Widmark formula to estimate your BAC as a percentage.
What is a safe blood alcohol level to drive?
There is no universally "safe" level — any amount of alcohol impairs driving. Legal limits vary by country: USA and UK allow 0.08%, most of Europe uses 0.05%, and some countries (Czech Republic, Hungary, Saudi Arabia) have zero tolerance. Always use a certified breathalyzer for legal decisions.
How long does it take for alcohol to leave your system?
Your body eliminates alcohol at approximately 0.015% BAC per hour. This means one standard drink (14g of alcohol) takes roughly 1-2 hours to metabolize. A BAC of 0.08% takes about 5.3 hours to reach zero. Factors like metabolism, food intake, and hydration affect this rate.
What is a standard drink?
A standard drink varies by country. In the USA it is 14 grams of pure alcohol (12 oz beer at 5%, 5 oz wine at 12%, or 1.5 oz spirits at 40%). In the UK it is 8 grams (1 unit). In most of Europe, including Estonia, it is 10 grams.
Why do men and women get different BAC results?
Women typically have a higher BAC than men after the same amount of alcohol because of biological differences in body water content and enzyme levels. The Widmark formula uses different distribution factors: 0.73 for males and 0.66 for females.
How accurate is a BAC calculator?
The Widmark formula has approximately 20% uncertainty. Actual BAC depends on many individual factors including metabolism, food consumption, liver health, medications, and hydration. This tool provides estimates only — never use it to decide if you are safe to drive.
What BAC level is dangerous or life-threatening?
BAC above 0.25% puts you at risk of alcohol poisoning with potential loss of consciousness. Above 0.35% can cause coma or death. Even at 0.10% there is significant motor impairment. If someone shows signs of alcohol poisoning, call emergency services immediately.
Is my data stored anywhere?
No. All calculations happen entirely in your browser. Your weight, sex, drink information, and BAC results are never sent to any server. This tool is 100% private and client-side.
All calculations happen locally in your browser. No personal or health data is sent to any server.