How Many Hours Until 0.00? A Table for 2, 4 and 6 Drinks at Three Body Weights
A calculated table of when blood alcohol reaches zero for 2, 4 and 6 drinks at three body weights, and the drive times it implies. Sleeping does not speed it up.
In this article9 sections
Six standard drinks finished at 11 p.m. put an 82 kg (180 lb) man near 0.15 g/dL at his highest point. By 6:30 a.m. he is down to about 0.04, comfortably under the common 0.08 limit, and at 8 a.m. he still reads about 0.02. Zero arrives around 9.
The usual answers to “when can I drive?” are “wait a day” or a confident “you’re fine after eight hours”. Neither comes from a calculation. This table does, and the hangover side of the morning, including which remedies have any evidence behind them, is a separate question from the driving side.
How the table was built
I used the Widmark formula, the standard forensic estimate: peak blood alcohol (g/dL) equals grams of alcohol divided by body weight in grams times a distribution ratio, times 100. I took a US standard drink as 14 grams of alcohol, a distribution ratio of 0.55 for the woman and 0.68 for the men, and an elimination rate of 0.015 g/dL per hour, the average widely used in forensic work (A.W. Jones’s reviews of ethanol elimination, in Forensic Science International, report individual rates scattered well above and below it). I assumed the whole amount was drunk by 11 p.m. and absorbed at once, which makes each peak an upper bound.
| Body | Drinks | Peak (g/dL) | Hours to 0.00 | Hours to fall below 0.05 | Hours to fall below 0.08 |
|---|---|---|---|---|---|
| 68 kg woman (150 lb) | 2 | 0.075 | 5.0 | 1.7 | 0 |
| 68 kg woman (150 lb) | 4 | 0.150 | 10.0 | 6.6 | 4.6 |
| 68 kg woman (150 lb) | 6 | 0.225 | 15.0 | 11.6 | 9.6 |
| 82 kg man (180 lb) | 2 | 0.050 | 3.3 | 0 | 0 |
| 82 kg man (180 lb) | 4 | 0.100 | 6.7 | 3.4 | 1.4 |
| 82 kg man (180 lb) | 6 | 0.151 | 10.0 | 6.7 | 4.7 |
| 95 kg man (210 lb) | 2 | 0.043 | 2.9 | 0 | 0 |
| 95 kg man (210 lb) | 4 | 0.087 | 5.8 | 2.4 | 0.4 |
| 95 kg man (210 lb) | 6 | 0.130 | 8.7 | 5.3 | 3.3 |
Which rows should change a plan
Count from the last sip. Six drinks that end at 11 p.m. mean the 82 kg man is not at zero until 9 a.m., and the 68 kg woman not until 2 p.m. the next day. A 7:30 a.m. school run after those six drinks finds the woman near 0.10, above the 0.08 limit, while the man at the same hour reads about 0.02.
A seven-hour night does nothing to those numbers. The liver works through alcohol at about the same pace whether the person is asleep or at a desk, and the 82 kg man above clears about 8 g of alcohol an hour, so one 14 g drink takes him roughly an hour and 40 minutes, so “I slept on it” is no measurement.
Where the legal lines fall
The general US limit is 0.08 g/dL in every state except Utah, which moved to 0.05 on December 30, 2018. England, Wales and Northern Ireland allow 80 mg per 100 ml of blood, the same number written differently, and Scotland has used 50 mg since December 2014. US commercial drivers are held to 0.04. Take the 68 kg woman after four drinks ending at 11 p.m. She falls under 0.08 at about 3:40 a.m. and under 0.05 at about 5:40. A 5 a.m. departure finds her near 0.06, legal in most of the US and over the line in Utah and Scotland.
For four drinks ending at 11 p.m., the 82 kg man is at zero by about 5:40 a.m., so a 7 a.m. commute finds him at zero and her near 0.03, with zero for her at 9.
Impairment can begin below any limit, and a hungover driver is a different driver from a rested one at the same reading. Short sleep adds its own risk, which AAA Foundation crash-odds data compares to drinking.
What the table cannot tell you
Elimination rates vary, with published ranges running from roughly 0.010 to 0.025 g/dL per hour, so a person at the slow end of that range needs about 50 percent more time than the table shows. Food in the stomach, the strength of a pour and the size of the glass change the real gram count, and a “drink” at a bar is often more than 14 grams. The formula also treats everyone of a given weight alike, which no body does. If the stakes are a license or another person’s safety, round up generously and take a ride. I am not a toxicologist, and a breathalyzer reading beats any table on a screen. Because the peaks assume instant absorption, real mornings often come in a bit lower than the table, but nothing here makes that safe to count on.
Quick answers before you check the table
How long does it take to sober up after 4 drinks?
For an 82 kg (180 lb) man, four US standard drinks of 14 g alcohol each produce a Widmark peak near 0.10 g/dL, which at an average elimination of 0.015 g/dL per hour reaches zero in about 6.7 hours. A 68 kg (150 lb) woman with the same four drinks peaks near 0.15 and needs about 10 hours.
Does sleep make the body clear alcohol faster?
No. Elimination runs at a roughly steady rate set by the liver, so eight hours in bed removes the same amount as eight hours awake, about 8 g of alcohol an hour, or 0.6 of a US drink, for an 82 kg man. Sleep changes the night and leaves the clearing rate alone.
Do coffee, cold showers or food speed up sobering up?
None of them raise the elimination rate in any meaningful way. Caffeine can make a person feel more alert while the blood concentration stays the same, which is the dangerous combination for a morning drive.
What are the legal blood alcohol limits for driving?
Every US state except Utah sets the general limit at 0.08 g/dL; Utah has used 0.05 since December 30, 2018. Scotland’s limit is 50 mg per 100 ml of blood, England and Wales use 80 mg, and US commercial drivers face 0.04.