Alcohol leaves your bloodstream at a steady rate of about 0.015% BAC per hour, which means a single standard drink is typically cleared in roughly one to two hours. But “staying in your body” can mean different things depending on whether you’re talking about feeling sober, passing a breathalyzer, or showing up on a urine test days later. The answer ranges from a few hours to several weeks, depending on the test.
How Your Body Breaks Down Alcohol
Your liver does the heavy lifting. It produces an enzyme that converts alcohol into a toxic intermediate compound called acetaldehyde (a known carcinogen), which is then quickly broken down into acetate, and finally into water and carbon dioxide that your body can easily get rid of. A secondary enzyme pathway kicks in only after heavy drinking, and a small amount of alcohol gets eliminated through breath, sweat, and urine without being processed by the liver at all.
What makes alcohol unusual is that your liver can only handle so much at once. Even at moderate blood alcohol levels, the main enzyme responsible for breaking down alcohol becomes fully saturated. Once that happens, your body eliminates alcohol at a fixed, constant rate no matter how much is in your system. This is why you can’t speed up sobering by drinking coffee or taking a cold shower. The only variable that matters is time.
The 0.015% Per Hour Rule
Your BAC drops by roughly 0.015 percentage points every hour. That number is remarkably consistent across most people, though the actual amount of alcohol processed (measured in grams per hour) varies based on body composition.
To put this in practical terms: if you stop drinking at midnight with a BAC of 0.08% (the legal limit for driving in most U.S. states), you won’t reach 0.00% until about 5:20 a.m. If your BAC is 0.15%, which is possible after several drinks in a short window, you’re looking at roughly 10 hours to fully clear your system. This is why people can still be legally impaired the morning after a night of heavy drinking.
A standard drink in the United States contains 14 grams of pure alcohol. That’s 12 ounces of regular beer (5% alcohol), 5 ounces of wine (12%), or 1.5 ounces of liquor (80-proof). Many cocktails and craft beers contain significantly more than one standard drink per serving, which makes it easy to underestimate how much alcohol is actually in your system.
Detection Windows by Test Type
Different tests look for different things. A standard blood or breath test measures the alcohol itself, which disappears relatively quickly. More advanced tests look for metabolic byproducts your body produces while breaking alcohol down, and those linger much longer.
- Breath: A breathalyzer typically detects alcohol for 4 to 6 hours after your last drink, though it can test positive for up to 24 hours.
- Blood (standard): Traditional blood alcohol tests detect consumption within the past 12 hours. Specialized blood tests measuring metabolic byproducts can detect drinking for up to 24 hours, and one type (PEth testing) can flag alcohol use from 1 to 3 weeks prior.
- Urine (standard ethanol): About 12 hours.
- Urine (EtG/EtS): These tests detect a metabolic byproduct rather than alcohol itself. They’re reliable for 24 to 48 hours in most cases. Sensitivity drops significantly after 24 hours for light drinking (a couple of drinks) but remains good for heavier consumption.
- Saliva: Up to 24 hours.
The “80-Hour Test” Is Overstated
You may have seen claims that EtG urine tests can detect alcohol for up to 80 hours. Research published through the National Institutes of Health found this is not supported by clinical evidence. In controlled studies, neither EtG nor its companion marker EtS was detectable much beyond 48 hours regardless of how much participants drank. The 80-hour claim appears to have originated from early, unsubstantiated marketing of the test. In practice, you should expect an EtG test to reliably catch moderate to heavy drinking within 24 to 48 hours, not 80.
Why Some People Process Alcohol Faster
The rate at which your body clears alcohol isn’t identical for everyone. The biggest factor is lean body mass, which alone accounts for about 40% of the variation between individuals. People with more lean tissue (muscle rather than fat) tend to process alcohol faster, largely because lean body mass correlates with liver size, and a bigger liver has more capacity to metabolize alcohol.
Biological sex plays a significant role too, but mostly because of body composition differences. In a study that controlled for variables using intravenous alcohol delivery (removing differences in gut absorption), women had an elimination rate roughly 27% lower than men on average. However, when researchers accounted for lean body mass, sex alone was no longer a significant predictor. In other words, the difference between men and women is primarily a difference in body composition and liver volume, not in the enzymes themselves.
Age, interestingly, does not appear to meaningfully change how fast your liver clears alcohol. The same study found no significant effect of age on elimination rate. Where age does matter is in how intensely you feel alcohol’s effects, but that’s separate from how long it stays in your system.
How Food Changes Absorption Speed
Eating before or during drinking doesn’t change how fast your liver processes alcohol, but it significantly changes how quickly alcohol reaches your bloodstream in the first place. Food slows the rate at which your stomach empties into the small intestine, where most alcohol absorption happens. This means your peak BAC is lower and takes longer to reach, even if you drink the same amount.
In a controlled clinical trial, participants who drank on an empty stomach hit peak blood alcohol in about 20 minutes. Those who ate a full mixed meal beforehand didn’t peak until 60 minutes, and their peak BAC was noticeably lower. The type of food matters too: meals high in protein, fiber, and viscous carbohydrates slow gastric emptying the most. A handful of crackers before drinking does far less than a full meal with protein and fat.
This has practical implications. Drinking on an empty stomach doesn’t just make you feel drunker faster; it produces a genuinely higher peak BAC, which means more impairment and a longer window before you’re back to zero.
What You Can and Can’t Control
No supplement, food, or remedy speeds up alcohol elimination once it’s in your bloodstream. Your liver works at its fixed rate of about 0.015% BAC per hour regardless of what you do. Drinking water, exercising, and eating after drinking may help you feel better, but they don’t lower your BAC any faster.
What you can control is the front end: how quickly alcohol enters your system. Eating a substantial meal before drinking, choosing lower-alcohol beverages, spacing drinks over more time, and alternating with water all reduce your peak BAC. A lower peak means less total time with alcohol in your body, less impairment, and a shorter window before you’d pass any form of testing.
For rough planning purposes, count your standard drinks, estimate your peak BAC (there are numerous online calculators that use your weight, sex, and number of drinks), and then divide by 0.015 to get the approximate hours until you’re at zero. Add a buffer, because most people undercount their drinks and overestimate how fast they metabolize alcohol.