EDUCATIONAL TOOL — NOT MEDICAL ADVICE A BAC estimate, not a fitness-to-drive determination — never drive after drinking.

Free Tool

BAC & Time to Sober Calculator

Blood alcohol concentration countdown — estimate your current BAC and the timeline until it's projected to return to 0.00%.

Number of Standard Drinks Hours Spent Drinking

Body Weight

Biological Sex

Drinking Habits

Clearance rate is approximate: Infrequent ~0.012 %/hr, Moderate ~0.015 %/hr, Heavy ~0.018 %/hr.

🕐 Enter your details to estimate your BAC timeline.

Estimated Current BAC

0.00%

Now 0.00% BAC

Hours Until Sober (0.00% BAC)

—

Blood Alcohol Calculator Over Time: How BAC Changes Hour by Hour

Empty wine glass and car keys with a blurred clock suggesting BAC falling over time

This page is a blood alcohol calculator over time: estimated BAC now, then a Widmark-style decline of about 0.015% per hour after peak (NIAAA teaching rate; the habit dropdown can use ~0.012 / 0.015 / 0.018). Coffee does not change the slope.

Worked example (170 lb male, 4 standard drinks, 2-hour sitting)

Peak BAC in the same teaching model used above is about 0.092%. After peak, hour-by-hour remaining BAC at 0.015%/hour:

Hours after peak	Estimated BAC
0	0.092%
1	0.077%
2	0.062%
3	0.047%
4	0.032%
5	0.017%
6	0.002%
7	0.00%

Estimated BAC vs hours after peak (0.015%/hour; educational, not a driving pass)

Enter your drinks in the calculator at the top of this page, then compare drink sizes on the BAC & legal limit calculator. Related guide: how long alcohol stays in your system.