Why Safe Resume Time Differs from the Legal Limit
Just because your BAC drops below the legal limit (0.03%) doesn't mean your judgment and reaction time are fully back to normal. This calculator uses the Widmark formula to estimate when alcohol is fully metabolized to near 0% BAC, then adds a 2-hour safety buffer to give you a "genuinely safe to drive" time.
How the Calculation Works
We calculate total alcohol grams from your drink type and count, then estimate peak BAC using body weight and a sex-based distribution ratio (0.68 for men, 0.55 for women). We apply the average elimination rate of 0.015% per hour since you stopped drinking to find current BAC, then add 2 hours to the time remaining until it reaches 0% to get your resume time.
Why Add a Buffer?
Even once BAC nears 0%, hangover fatigue, sleep deprivation, and reduced focus can linger. Traffic safety research shows hungover drivers have slower reaction times regardless of current BAC, which is why an extra buffer after full metabolism is recommended.
Important Notes
This calculator provides a reference estimate only — actual metabolism speed varies significantly with liver health, food intake, sleep quality, and individual constitution. Even after the calculated time arrives, if you still feel sluggish or drowsy, don't push through — rest more before you drive.
Frequently Asked Questions
Yes. We calculate when BAC is fully metabolized to near 0% and add a 2-hour safety buffer.
Even below 0.03%, reaction time and judgment may not be fully normal, so we recommend the added buffer.
No. It varies by individual metabolism and condition — use this as a reference only.