BAC Calculator
Estimate blood alcohol concentration from body weight, standard drinks and time using a simplified Widmark model, with a strong driving-safety warning.
Enter your values
Change any assumption and calculate again to compare results.
Educational estimate only
This calculator uses a simplified Widmark-style model. It assumes about 14 grams of pure alcohol per U.S. standard drink, a sex-based body-water distribution factor and an average elimination rate of 0.015 percentage points of BAC per hour.
Real BAC can differ substantially because drink size, alcohol concentration, food, absorption speed, body composition, medications, liver function and timing vary. A calculator cannot determine whether you are safe or legally fit to drive.
Do not use this result to decide whether to drive
If you have consumed alcohol, the safest choice is not to drive. BAC can continue to rise after the last drink, and impairment can exist below a legal threshold.
Use a sober driver, taxi, rideshare or public transport. If there is concern about alcohol poisoning, loss of consciousness, slow or irregular breathing, repeated vomiting or inability to wake someone, seek emergency help.
What counts as a standard drink
A standard drink is an amount containing roughly 14 grams of pure alcohol in the United States. Real servings can contain more than one standard drink.
Because the input asks for standard drinks rather than glasses or cans, convert large or strong servings appropriately before using the estimate.
Important information
This calculator is for general education and planning. It is not a diagnosis, medical device or substitute for individualized healthcare advice. Measurements and formula estimates can differ from clinical assessments.
If the result could affect treatment, pregnancy care, medication, driving, military status or another safety-sensitive decision, confirm it with the appropriate qualified professional or official process.
Frequently Asked Questions
Can this tell me if I am safe to drive?
No. Never use a BAC calculator to decide whether to drive or perform a safety-sensitive task.
Why can actual BAC be different?
Absorption, drink strength, food, body composition, metabolism and timing vary between people and occasions.
What does one standard drink mean here?
The model assumes about 14 grams of pure alcohol per standard drink.