How long until you are sober

The two times the calculator shows

After the estimate, the calculator gives a typical time to reach 0.0 and a cautious, later time. The typical time uses the average elimination rate of 14.8 mg per 100 mL per hour — about 0.15 g/L per hour. The cautious time assumes a slower eliminator at the edge of the likely range, so it sits well past the typical one. Both are counted from your first drink, and both are shown as a clock time as well as a number of hours, so you can read straight off when each is reached.

Nothing but time works

The liver clears alcohol at a roughly fixed pace that you cannot rush. Coffee, a cold shower, a walk, or sleeping it off do not lower BAC — coffee and cold water can make a person feel more awake while their driving is still impaired, which is its own danger (NIAAA). Because the rate is roughly fixed, doubling the alcohol roughly doubles the wait. Two drinks that clear in about an hour and a half become four drinks that take about three.

Watch the rising phase

In the first while after drinking, BAC can still be rising rather than falling: alcohol left in the stomach and intestine keeps entering the blood after the last sip (NIAAA). The peak usually comes some time after the last drink, not at the moment you stop. So a low reading taken right after drinking is not a safe reading — it may climb before it falls. The time-to-zero already accounts for this; the reading you see now does not.

Sources