A single alcoholic drink takes roughly one hour to leave your bloodstream. Your liver lowers your blood alcohol concentration (BAC) by about 0.015 per hour, which is a fixed rate that doesn’t speed up no matter what you do. But “in your system” can mean different things depending on the type of test, and some markers of drinking linger far longer than the alcohol itself.
How Your Body Processes Alcohol
Your liver does the heavy lifting. An enzyme called alcohol dehydrogenase breaks ethanol into acetaldehyde, then a second enzyme converts that into acetic acid, which your body can use for energy or dispose of. This two-step process handles the vast majority of the alcohol you drink. Only about 5% leaves your body unchanged through urine, sweat, and breath, which is why a breathalyzer works but only captures a tiny fraction of what’s actually in your system.
The 0.015 BAC-per-hour rate is remarkably consistent across people. It means that if your BAC reaches 0.08 (the legal driving limit in most U.S. states), you’d need roughly five and a half hours of zero additional drinking before your blood is alcohol-free. A BAC of 0.15, which is nearly twice the legal limit, would take about ten hours.
What Counts as One Drink
A standard drink in the United States contains 0.6 ounces (14 grams) of pure alcohol. That equals 12 ounces of regular beer at 5% alcohol, 5 ounces of wine at 12%, or a 1.5-ounce shot of 80-proof liquor. Craft beers, heavy pours of wine, and strong cocktails often contain more than one standard drink per glass, so your actual intake may be higher than you think.
One standard drink typically raises BAC by about 0.02 to 0.03 in an average-sized person, though this varies with body weight and composition. At the fixed elimination rate of 0.015 per hour, a single drink clears your blood in roughly one to two hours. Two drinks might take three hours, three drinks around four to five hours, and so on.
When BAC Peaks
Your blood alcohol level doesn’t peak the moment you finish a drink. On an empty stomach, BAC peaks about one hour after drinking. Food changes this significantly. Eating a full meal before or while drinking can reduce the amount of alcohol that actually reaches your bloodstream by roughly 30%, compared to drinking while fasting. A meal both lowers the peak BAC and delays it, because food slows the rate at which alcohol moves from your stomach into the small intestine, where most absorption happens.
This is why the same number of drinks can hit much harder on an empty stomach. It’s also why your BAC can still be rising even after you’ve stopped drinking, especially if you had several drinks in a short period.
Detection Windows by Test Type
How long alcohol shows up on a test depends entirely on what’s being measured:
- Blood and breath: These detect alcohol itself and generally show positive results for up to 12 to 24 hours after heavy drinking, though moderate drinking clears faster. A breathalyzer mirrors your current BAC closely.
- Urine (standard): A basic urine test detects alcohol for a similar window as blood, roughly 12 to 24 hours.
- Urine (EtG): This test looks for ethyl glucuronide, a byproduct your body creates when processing alcohol. EtG lingers far longer than alcohol itself. After a few drinks, it can show up in urine for up to 48 hours. Heavier drinking can push detection to 72 hours or beyond. Testing labs typically use a cutoff of 100 or 500 nanograms per milliliter depending on whether the context is clinical or forensic.
- Hair: Hair follicle tests also detect EtG markers and can reveal alcohol use from one to six months in the past. The standard testing window is three to six months, limited mainly by how often someone cuts their hair.
What Affects How Fast You Clear Alcohol
Genetics play the biggest role. Variations in the enzymes that break down alcohol are inherited, and they differ across populations and individuals. Some people produce more efficient versions of these enzymes, while others produce less active forms that slow the process or cause unpleasant flushing reactions.
Body size and composition matter too. A larger person has more blood volume, so the same amount of alcohol produces a lower BAC. Women generally reach higher BAC levels than men of the same weight after the same number of drinks, partly due to differences in body water content and enzyme activity. Age can also slow metabolism, as liver function gradually declines over time.
People who drink heavily over long periods may activate a secondary enzyme pathway that helps process alcohol when the primary system is overwhelmed. This is one reason chronic heavy drinkers can appear more tolerant, though it comes with its own health costs.
Why Exercise and Water Don’t Help
A common belief is that working out, drinking water, or taking a cold shower will sober you up faster. None of these change the rate your liver breaks down alcohol. Your muscles don’t use alcohol as fuel, so exercise has no effect on clearance. Water and coffee can help with hydration and alertness, but they won’t lower your BAC any faster. The only thing that eliminates alcohol from your blood is time.
Since roughly 95% of alcohol is metabolized by the liver at a fixed pace, the small percentage lost through sweat, urine, and breath is too minor to meaningfully speed things up, even with vigorous activity.
Practical Timelines
For a rough estimate of when your blood will be alcohol-free, take your estimated peak BAC and divide by 0.015. If you had three drinks over two hours and estimate a peak BAC around 0.06 to 0.07, you’re looking at four to five hours from your last drink before it’s fully cleared from your blood. For a night of heavier drinking where BAC reaches 0.12 or higher, clearance could take eight hours or more.
Keep in mind that feeling sober and being at a BAC of zero are not the same thing. Your brain adjusts to alcohol’s effects over the course of a drinking session, so you may feel relatively normal while still carrying a measurable BAC. If you’re concerned about a drug test rather than driving, EtG urine testing extends the relevant window well beyond when you feel the effects. For most moderate drinkers, a 48-hour window after your last drink is a reasonable minimum to clear an EtG screen, with 72 hours or more providing a larger safety margin after heavier consumption.