Alcohol is typically eliminated from your bloodstream within 12 hours of your last drink, but it can be detected in urine for up to 72 hours and in hair for several months. The exact timeline depends on how much you drank, your body’s metabolism, and which type of test is being used.
How Your Body Processes Alcohol
Your liver does the heavy lifting. It produces an enzyme that breaks alcohol into smaller compounds your body can eliminate, reducing your blood alcohol concentration (BAC) by about 0.015 per hour. That rate is remarkably consistent from person to person, and there’s no reliable way to speed it up. Coffee, cold showers, and “sweating it out” don’t change the math.
To put that in practical terms: a single standard drink (a 12-ounce beer, 5-ounce glass of wine, or 1.5-ounce shot of liquor) contains about 14 grams of pure alcohol. For most people, that raises BAC by roughly 0.02 to 0.03. At the fixed clearance rate of 0.015 per hour, one drink takes about one to two hours to fully process. Three drinks might take four to six hours. A night of heavier drinking could leave alcohol in your blood well into the next morning.
Detection Windows by Test Type
Different tests look for different things, and that changes how far back they can reach.
- Blood: Up to 12 hours. Blood tests measure active alcohol circulating in your system, so the window closes relatively quickly.
- Breath: 12 to 24 hours. A breathalyzer estimates BAC from alcohol vapor in your lungs. For moderate drinking, detection usually fades within 12 hours, but heavier consumption can push that closer to 24.
- Saliva: Up to 24 hours. Oral fluid tests work on a similar timeline to breath tests.
- Urine (standard): 12 to 24 hours for a basic ethanol urine screen.
- Urine (EtG): 48 to 72 hours or longer. This test looks for a specific byproduct your body creates when it processes alcohol. After a few drinks, this marker can show up in urine for two days. Heavier drinking can extend detection to 72 hours or beyond.
- Hair: Up to 90 days, and sometimes longer. Hair follicle tests detect the same EtG marker that gets incorporated into growing hair strands. Results typically cover one to six months, though most labs use the standard 90-day window based on 1.5 inches of hair growth.
The EtG urine test is worth knowing about specifically because it catches people off guard. Workplace and court-ordered testing programs increasingly use it instead of standard urine screens, and its detection window is roughly three times longer.
What Affects How Fast You Clear Alcohol
While the 0.015 BAC-per-hour rate is a reliable average, several factors influence how quickly your BAC rises in the first place and, to a lesser degree, how efficiently your liver works through it.
Genetics play a significant role. The enzymes responsible for breaking down alcohol vary from person to person based on inherited gene variants. Some people produce more active versions of these enzymes and process alcohol faster. Others, particularly many people of East Asian descent, carry enzyme variants that cause a toxic intermediate compound to build up, leading to facial flushing, nausea, and a slower overall clearance.
Body weight and composition matter because alcohol is water-soluble. A larger person with more body water will dilute the same amount of alcohol across a greater volume, resulting in a lower peak BAC. This is also one reason women generally reach higher BAC levels than men after the same number of drinks: women tend to have proportionally less body water and more body fat, concentrating the alcohol more.
Food makes a meaningful difference in absorption. Eating before or while drinking slows the rate at which alcohol moves from your stomach into your small intestine, where most absorption happens. Research published in the Journal of Studies on Alcohol found that eating any type of food, whether high in fat, protein, or carbohydrate, lowered peak blood alcohol levels and delayed the time it took to reach that peak. You still absorb all the alcohol eventually, but the slower rise gives your liver more time to keep up, so your BAC doesn’t spike as high.
Age tends to slow metabolism. Liver function gradually declines over the decades, and older adults often have less body water, both of which mean alcohol lingers longer. Medications that compete for the same liver enzymes can also slow processing.
How Many Drinks Take How Long to Clear
Here’s a rough guide based on the average elimination rate of 0.015 BAC per hour. These assume you stopped drinking and your BAC has already peaked.
- 1 to 2 standard drinks: Roughly 2 to 4 hours to reach 0.00 BAC.
- 3 to 4 standard drinks: Roughly 4 to 8 hours.
- 5 to 7 standard drinks: Roughly 8 to 14 hours.
- 8 or more standard drinks: Could take 16 hours or longer.
These numbers explain why someone who drinks heavily on a Saturday night can still blow a positive breathalyzer Sunday morning, or why a Monday-morning EtG urine test can flag weekend drinking. The gap between feeling sober and actually being alcohol-free is often several hours. Your body finishes processing the last of the alcohol long after the buzz wears off.
Why You Can’t Speed It Up
Your liver processes alcohol at a fixed enzymatic rate. No supplement, food, or activity has been shown to meaningfully accelerate that. Drinking water helps with dehydration but doesn’t lower BAC faster. Exercise increases breathing rate slightly, but since only a tiny fraction of alcohol leaves through your lungs, the effect is negligible. The only thing that reliably clears alcohol from your system is time.
What you can control is the front end: how quickly alcohol enters your bloodstream. Drinking slowly, eating beforehand, and alternating alcoholic drinks with water all help keep your peak BAC lower, which means less total time before you’re back to zero.