Blood Alcohol Calculator

Enter your drinks, weight, and time elapsed to estimate your Blood Alcohol Concentration (BAC). A free online BAC calculator based on the Widmark formula.

Frequently Asked Questions

What is Blood Alcohol Concentration (BAC)?
BAC measures the percentage of alcohol in your bloodstream. In many jurisdictions, the legal limit for driving is 0.08%. Even lower BAC levels can impair judgment and reaction time.
What is the Widmark formula?
The Widmark formula estimates BAC using alcohol consumed, body weight, gender, and elapsed time: BAC = (alcohol consumed / (body weight × body water constant)) - (elapsed hours × metabolism rate).
Is the calculated BAC accurate?
This calculator provides an estimate only. Actual BAC varies based on individual metabolism, food intake, medications, and overall health. Never rely solely on a calculator to determine fitness to drive.
Updated 2026 pricing