Blood Alcohol Calculator
Estimate your blood alcohol content (BAC) based on drinks consumed, body weight, and time elapsed.
Disclaimer: This calculator is for educational purposes only. Results are estimates and should not be used to determine if you are fit to drive or operate machinery. When in doubt, do not drive.
Widmark Formula
Uses the scientifically-backed Widmark formula for accurate BAC estimation.
Time-Based Metabolism
Accounts for alcohol metabolism over time at the standard 0.015% per hour rate.
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All calculations happen in your browser. Your data is never sent to any server.
Frequently Asked Questions
How is blood alcohol content (BAC) calculated?
BAC is calculated using the Widmark formula: BAC = (alcohol consumed in grams / (body weight x r)) - (0.015 x hours). The r factor is 0.68 for males and 0.55 for females, accounting for body water distribution differences.
What is the legal BAC limit for driving?
In most US states, the legal limit is 0.08% BAC. However, impairment begins at lower levels, and some jurisdictions have lower limits. Commercial drivers often have a 0.04% limit.
How long does it take for alcohol to leave your system?
On average, your body metabolizes alcohol at a rate of about 0.015% BAC per hour. This rate is relatively constant and cannot be sped up by coffee, food, or water.
Why do men and women have different BAC calculations?
Women generally have a higher body fat percentage and lower body water content than men. Since alcohol dissolves in water, women typically reach higher BAC levels from the same amount of alcohol.
What factors affect BAC besides weight and gender?
Other factors include food consumption, medication interactions, liver health, hydration level, and individual metabolism. This calculator provides estimates only.
Is this calculator accurate for determining if I can drive?
No. This calculator provides estimates for educational purposes only. Many factors can affect actual BAC. Never rely on any calculator to determine if you are safe to drive. When in doubt, do not drive.