How does the Widmark formula calculate BAC?+
The Widmark formula estimates BAC as: BAC = (grams of alcohol consumed / (body weight in grams x Widmark r factor)) - (0.015 x hours since first drink). The Widmark r factor accounts for differences in body water distribution between genders (0.68 for men, 0.55 for women). The 0.015 rate represents the average hourly elimination rate of alcohol.
What is a standard drink in the U.S.?+
A U.S. standard drink contains about 14 grams (0.6 fluid ounces) of pure alcohol. This is roughly equivalent to 12 ounces of regular beer (5% ABV), 5 ounces of wine (12% ABV), or 1.5 ounces of distilled spirits (40% ABV / 80 proof). Many cocktails and craft beers contain more than one standard drink.
Is this BAC calculator accurate?+
This calculator provides only a rough estimate. Actual BAC is influenced by many factors not considered here, including food intake, medications, liver health, hydration status, individual metabolism, genetics, and body composition. Two people of the same weight and gender can have very different BACs after drinking the same amount. Never rely on a calculator to judge whether it is safe to drive.
What BAC level is considered drunk driving?+
In the U.S., the legal driving limit for drivers aged 21 and over in all 50 states is 0.08% BAC. Commercial drivers (CDL holders) have a lower limit of 0.04%. Drivers under 21 face zero-tolerance laws, typically 0.00-0.02% depending on the state. Many countries have lower limits, such as 0.05% in Australia and most of Europe.
How long does alcohol take to leave the body?+
On average, the body eliminates alcohol at a rate of about 0.015% BAC per hour, roughly equal to one standard drink per hour. However, this rate varies from person to person. A person with a BAC of 0.08% would need about 5.3 hours to reach 0.00%. There is no way to speed up the process; coffee, cold showers, and exercise will not lower BAC faster.
Why does body weight affect BAC?+
Alcohol distributes through body water. Larger people typically have more body water to dilute the alcohol, resulting in a lower BAC for the same amount of alcohol. This is also why the Widmark factor differs by gender: men generally have a higher body water percentage (68%) than women (55%), meaning the same amount of alcohol at the same weight typically produces a higher BAC in women.
Can I use this calculator to know if it is safe to drive?+
No. This calculator is for educational and informational purposes only. The rough estimate it provides can differ significantly from your actual BAC. Impairment can occur even below legal limits. The only safe amount of alcohol to consume before driving is zero. If you have been drinking, use a designated driver, ride-share service, or taxi.