Alcohol is detectable in your body for anywhere from 12 hours to 90 days, depending on the type of test. Your liver clears alcohol from your blood at a fixed rate of about 0.015 BAC per hour, which works out to roughly one standard drink per hour. But traces of alcohol’s byproducts linger much longer than the alcohol itself.
Detection Windows by Test Type
Different tests look for different things. Some measure alcohol directly, while others detect metabolites your body produces while breaking alcohol down. Here’s how long each test can pick up a positive result:
- Blood: up to 12 hours after your last drink
- Breath (breathalyzer): 12 to 24 hours, depending on how much you drank
- Urine (standard): 12 to 24 hours for direct ethanol detection
- Urine (EtG metabolite test): typically 48 to 72 hours, and up to 5 days after heavy drinking
- Hair follicle: up to 90 days
The urine distinction matters. A standard urine test looks for alcohol itself and has a short window. An EtG test looks for ethyl glucuronide, a byproduct your body creates while processing alcohol. EtG tests are common in court-ordered monitoring, probation, and workplace programs precisely because they catch drinking days after the fact.
How Your Body Processes Alcohol
Your liver does the heavy lifting. It produces an enzyme that breaks alcohol into a toxic intermediate compound called acetaldehyde (the substance partly responsible for hangovers). A second enzyme then quickly converts acetaldehyde into acetate, which is harmless. Acetate eventually gets broken down into carbon dioxide and water throughout the body.
This process runs at a nearly constant speed. Your liver reduces your BAC by about 0.015 per hour regardless of how much you’ve had. You can’t speed it up with coffee, water, food, or cold showers. Those might help you feel more alert, but your BAC drops at the same steady pace no matter what.
Realistic Timelines for Common Scenarios
One standard drink raises most people’s BAC to somewhere around 0.02 to 0.04, depending on body size and other factors. At the average elimination rate, that takes roughly one to two hours to clear completely. Three standard drinks over an hour might put you around 0.06 to 0.08 BAC, meaning you’d need four to five hours to return to 0.00.
A night of heavier drinking is where people underestimate the math. If you stop drinking at midnight with a BAC of 0.12, your body won’t reach 0.00 until about 8:00 a.m. If you hit 0.15, you’re looking at 10 hours. This is why people sometimes blow positive on a breathalyzer the morning after a night out, even though they feel sober.
For reference, one standard drink in the U.S. contains about 14 grams of pure alcohol. That’s a 12-ounce beer at 5% ABV, a 5-ounce glass of wine at 12% ABV, or a 1.5-ounce shot of liquor at 40% ABV. Many craft beers, cocktails, and generous pours contain significantly more than one standard drink, so you may be consuming more than you think.
Factors That Change How Long Alcohol Stays
While the liver’s elimination rate is fairly consistent across people, several factors affect how high your BAC gets in the first place and how efficiently your body clears it.
Biological Sex
Women typically reach higher peak BAC levels than men after drinking the same amount, adjusted for body weight. This happens because women generally carry a higher proportion of body fat, and alcohol doesn’t dissolve well in fat. The result is a smaller volume of body water for the alcohol to distribute into, creating a more concentrated BAC. Women may also have less of the stomach enzyme that begins breaking down alcohol before it reaches the bloodstream.
Body Size and Composition
Two people who weigh the same can reach very different BAC levels from the same number of drinks if their body compositions differ. Someone with more muscle and less fat has more body water for alcohol to spread into, which dilutes the concentration. This is why BAC calculators that rely on weight alone are only rough estimates.
Whether You’ve Eaten
Food in your stomach is one of the biggest variables. Eating slows the rate at which alcohol passes into your small intestine, where most absorption happens. On an empty stomach, alcohol moves quickly into the intestine, gets absorbed rapidly, and produces a higher, faster peak BAC. Eating before or while drinking also slightly increases your liver’s processing speed, since the enzymes responsible for breaking down alcohol are more active in a fed state.
Genetics
A genetic variation common in people of East Asian descent affects the second enzyme in the breakdown chain. People with one copy of this variant break down the toxic intermediate (acetaldehyde) more slowly, leading to facial flushing, nausea, and a rapid heartbeat after drinking. Those with two copies of the variant can have blood acetaldehyde levels up to 18 times higher than people without it. This doesn’t just cause unpleasant symptoms; it means the overall process of clearing alcohol from the body is disrupted.
Age
Alcohol elimination may slow slightly with age, likely due to reduced liver mass and lower total body water content. The change isn’t dramatic, but older adults often notice that the same amount of alcohol hits harder and takes longer to wear off than it did in their younger years.
Why You Can’t Speed It Up
Your liver can only process a fixed amount of alcohol per hour because the enzymes involved work at a set capacity. Once those enzymes are fully occupied, any excess alcohol stays circulating in your blood until the enzymes are free again. No supplement, food, or activity changes this bottleneck. The only thing that actually clears alcohol from your system is time.
If you’re trying to gauge whether you’re safe to drive or will pass a test, the most reliable approach is conservative math: count your drinks honestly, figure roughly one hour per standard drink after you stop, and add a buffer. Your BAC peaks about 30 to 60 minutes after your last drink, so the clock doesn’t start the moment you put down your glass.