Blood Alcohol Calculator (BAC)
Enter your drinks and see an estimated BAC — an educational guide, never a green light to drive.
Sex
Sex sets the Widmark r factor (0.68 male / 0.55 female, population averages).
Drinks
Add each drink you had. Presets use typical serving sizes; choose Custom to enter your own volume and ABV.
Estimated current BAC
≈ 0.00 % — alcohol has likely been metabolized.
Potentially life-threatening range — seek emergency help immediately.
Legal BAC limits vary by country — e.g. 0.03% in Korea and Japan, 0.05% across much of the EU, 0.08% in the US and UK, and zero for novice or commercial drivers in many places.
This is a rough statistical estimate from the Widmark formula. Real BAC depends on food, metabolism, medication and health, and can be higher than shown. Never use this tool to decide whether to drive.
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What is the Widmark formula and how is BAC estimated?
The Widmark formula is the classic way to estimate blood alcohol content (BAC). This blood alcohol calculator adds up the pure ethanol in your drinks in grams (A), then computes peak BAC = A ÷ (body weight in grams × r) × 100, where r is a body-water constant (0.68 for men, 0.55 for women). It then subtracts the alcohol your liver has already burned off — about 0.015% per hour — to estimate your current BAC. It is the same Widmark formula calculator method used in textbooks, applied entirely in your browser.
How accurate is this, and why can't I trust it to decide to drive?
Treat every number here as a rough educational estimate, not a measurement. Real BAC varies widely with food in your stomach, how fast you drank, body composition, liver health, medication and even the day. Two people of the same weight can end up far apart, and your true BAC can be higher than this calculator shows. Only a breathalyzer or blood test measures your actual level — so never use a BAC calculator to decide whether it is safe to drive. If you have been drinking, do not drive.
How long does it take for alcohol to leave your system?
Your body clears alcohol at a fairly steady rate of roughly 0.015% BAC per hour, and only time lets the liver do this work. Coffee, cold showers, water, food and fresh air can make you feel more alert but do not speed up how fast alcohol leaves your system. This calculator shows an estimated time until your BAC falls below common limits and back to about 0.00%, but the safest assumption is always to allow more time than the estimate suggests.
What are the legal BAC limits around the world?
Legal driving limits differ by country: about 0.03% in South Korea and Japan, 0.05% across much of Europe, and 0.08% in the United States and the United Kingdom. Many places set a zero or near-zero limit for novice, young or commercial drivers. Because the threshold that counts as "over the limit" depends on where you are, this tool shows reference lines rather than a single pass/fail — and being under a limit still does not mean you are safe to drive.
Is my drinking data sent anywhere?
No. This blood alcohol calculator runs 100% in your browser. Your sex, weight, drinks and hours are used only to compute an estimate on your device and are never uploaded to any server. For convenience they are saved to your browser's localStorage so the form is ready next time, and you can clear them anytime by clearing your site data.