Alcohol leaves your bloodstream at a fixed rate of about 0.015 BAC per hour, which means a single drink takes roughly one to two hours to clear. But “your system” is broader than your blood. Depending on the type of test, alcohol or its byproducts can be detected anywhere from 12 hours to 6 months after your last drink.
How Fast Your Body Processes Alcohol
Your liver does nearly all the work of breaking down alcohol, using an enzyme that reduces your blood alcohol concentration (BAC) by about 0.015 per hour. That rate is remarkably consistent from person to person and can’t be sped up by coffee, food, water, or exercise once the alcohol is already in your bloodstream.
To put that in practical terms: if you stop drinking at midnight with a BAC of 0.08 (the current legal limit in most U.S. states), your body needs roughly five and a half hours to bring that number to zero. A heavier night of drinking that pushes your BAC to 0.15 would take about ten hours. One standard drink in the U.S. contains 14 grams of pure alcohol, which is the amount in a 12-ounce beer, a 5-ounce glass of wine, or a 1.5-ounce shot of liquor. Each one of those adds roughly 0.02 to 0.03 to your BAC, depending on your weight and sex.
Detection Windows by Test Type
The answer to “how long does alcohol stay in your system” depends entirely on what’s being tested.
- Blood: A standard blood alcohol test can detect alcohol for up to about 12 hours after your last drink.
- Breath: Breathalyzers track alcohol in your lungs and generally align with your blood alcohol timeline, detecting it for roughly 12 to 24 hours depending on how much you drank.
- Standard urine test: A basic urine test for ethanol picks up alcohol for about 12 to 24 hours.
- EtG urine test: This more sensitive test doesn’t look for alcohol itself but for a metabolic byproduct your body creates while processing it. After a few drinks, this byproduct can show up in urine for up to 48 hours. After heavier drinking, it can be detected for 72 hours or longer.
- Hair follicle: Alcohol markers can be found in hair for 1 to 6 months, though most results cover 3 to 6 months because people cut or trim their hair before the full window passes.
The EtG urine test is the one most commonly used in court-ordered testing, workplace monitoring, and substance abuse programs precisely because its window is so much wider than a standard blood or breath test.
What Affects How Quickly You Feel Sober
While the liver’s elimination rate stays relatively fixed, several factors change how high your BAC climbs in the first place, which in turn determines how long it takes to come back down.
Food is the biggest variable. Eating before or while drinking slows the release of alcohol from your stomach into your small intestine, where absorption happens rapidly. Research on alcohol absorption shows that after a heavy meal, alcohol is released into the small intestine so slowly that peak BAC is significantly lower than it would be on an empty stomach. In animal studies, 10 to 20 percent of an alcohol dose was still sitting in the stomach four hours later when food was present. The practical takeaway: drinking on a full stomach doesn’t prevent intoxication, but it spreads it out and keeps your BAC from spiking as high.
Body weight and composition also matter. A larger person has more blood volume, so the same amount of alcohol is more diluted. Women generally reach higher BAC levels than men of the same weight after the same number of drinks, partly because of differences in body water content and partly because of differences in how much alcohol is broken down in the stomach before reaching the bloodstream.
Liver Health and Alcohol Clearance
You might assume that people with liver damage process alcohol more slowly, but research on this is surprisingly mixed. Studies comparing people with liver cirrhosis to those with healthy livers have found that the rate of alcohol disappearance from blood in healthy subjects falls within 9 to 20 mg/dL per hour, and there’s no strong evidence that cirrhotic patients are much different. That said, liver disease affects tolerance, overall health, and the risk of dangerous complications from drinking, even if the raw metabolism speed holds relatively steady.
Legal BAC Limits
In most U.S. states, the legal limit for driving is 0.08 BAC. For commercial vehicle operators, it’s 0.04. Some jurisdictions are considering lowering these thresholds. New York, for example, has introduced legislation that would drop the standard DUI limit to 0.05 and the aggravated DUI threshold from 0.18 to 0.12.
At the standard elimination rate of 0.015 per hour, someone right at 0.08 needs at least five hours of not drinking before they’re technically legal to drive. But people routinely underestimate their BAC, especially after drinking over several hours. If your last drink was at 1 a.m. and you’re driving at 6 a.m., you could still be above the legal limit depending on how much you consumed earlier in the night.
A Rough Timeline for Common Scenarios
These estimates assume average body weight and a standard elimination rate of 0.015 BAC per hour:
- 2 drinks over an hour: Alcohol clears your blood in roughly 3 to 4 hours. Detectable on an EtG urine test for up to 24 to 48 hours.
- 4 drinks over two hours: Blood alcohol returns to zero in about 5 to 7 hours. EtG detection extends to 48 hours or more.
- 8 or more drinks over an evening: Blood alcohol could take 10 to 15 hours to clear entirely. EtG may be detectable for 72 hours or longer.
Nothing you do after drinking changes these timelines. The liver processes alcohol at its own pace, and the only thing that actually sobers you up is time.