Alcohol is detectable in your body for as little as 6 hours or as long as 6 months, depending entirely on which test is used. Your liver clears roughly one standard drink per hour, but the byproducts of that process linger in urine and hair far longer than alcohol itself stays in your blood.
Detection Windows by Test Type
This is the chart most people are looking for. Each testing method picks up either alcohol itself or a metabolic byproduct, which is why the detection windows vary so dramatically.
- Blood: Up to 12 hours after your last drink
- Breath: Up to 24 hours (standard breathalyzers measure alcohol still circulating from your lungs)
- Urine (standard): 12 to 24 hours for alcohol itself
- Urine (EtG test): 48 to 72+ hours, depending on how much you drank
- Hair follicle: Up to 90 days as a standard testing window, though markers can persist for 6 months or longer
The wide gap between a blood test and a hair test comes down to what’s being measured. Blood and breath tests detect ethanol directly, so once your liver finishes processing it, those tests come back clean. Urine EtG tests and hair tests look for a byproduct called ethyl glucuronide, a marker your body produces only when processing alcohol. That marker gets trapped in growing hair strands and can be found in urine days after the alcohol itself is gone.
How Your Body Processes Alcohol
Your liver does about 95% of the work. It uses an enzyme to convert ethanol into a toxic compound called acetaldehyde (a known carcinogen), then quickly converts that into acetate, which breaks down into water and carbon dioxide that your body eliminates easily. This two-step process runs at a fixed speed: roughly one standard drink per hour. You can’t speed it up with coffee, food, water, or exercise. Time is the only thing that clears alcohol from your system.
A “standard drink” in the United States contains about 14 grams of pure alcohol. That’s a 12-ounce beer at 5% alcohol, a 5-ounce glass of wine at 12%, or a 1.5-ounce shot of liquor at 40%. Many cocktails and craft beers contain significantly more than one standard drink, which means your liver needs more time than you might expect.
Estimated Clearance by Number of Drinks
Since the liver processes approximately one drink per hour, you can roughly estimate how long alcohol will remain in your blood based on how much you consumed:
- 1 standard drink: About 1 to 2 hours
- 2 standard drinks: About 2 to 3 hours
- 3 standard drinks: About 3 to 4 hours
- 4 standard drinks: About 4 to 5 hours
- 5 standard drinks: About 5 to 7 hours
- 8 standard drinks: About 8 to 11 hours
These are estimates for blood and breath detection. EtG urine tests run on a completely different timeline. After just a few drinks, EtG can show up in urine for 48 hours. After heavier drinking, that window stretches to 72 hours or more, according to research from the Medical University of South Carolina.
What Changes Your Personal Timeline
The “one drink per hour” rule is an average, not a guarantee. Several biological factors shift your actual clearance rate in either direction.
Body size and composition play a major role. A larger person with more water in their body will dilute alcohol more effectively, resulting in a lower peak blood alcohol concentration from the same number of drinks. Muscle tissue contains more water than fat tissue, so two people at the same weight can process alcohol differently based on their body composition.
Biological sex matters too. Women generally absorb more alcohol and take longer to process it than men, even when drinking the same amount. The CDC attributes this to differences in body size, muscle mass, body fat percentage, and hormones. This means women typically reach higher blood alcohol levels faster and stay at those levels longer.
Other factors include whether you’ve eaten recently (food slows absorption, giving your liver more time to keep up), how quickly you drank, your age, liver health, and genetics. Some people produce more or less of the enzymes responsible for breaking down alcohol, which directly affects how quickly they clear it.
Why the Test Type Matters
If you’re trying to figure out how long alcohol stays in your system, you’re probably anticipating a specific type of test. The context determines which detection window applies to you.
Standard workplace and legal tests typically use breath or blood. Department of Transportation testing, for example, uses breath or saliva for screening and confirms results with an evidential breath testing device. The DOT flags any result at or above 0.02 blood alcohol concentration and considers 0.04 or higher a violation. For these tests, you’re generally looking at a 12 to 24 hour window.
Court-ordered monitoring, probation checks, and some medical settings use EtG urine tests specifically because they catch drinking that happened two to three days earlier. These tests are sensitive enough to detect even moderate drinking well after you feel completely sober. A single night of heavy drinking on Friday could still produce a positive EtG result on Monday morning.
Hair follicle tests are less common but cover the longest window. Labs typically analyze the most recent 1.5 inches of hair growth, which represents roughly 90 days. These tests identify patterns of repeated drinking rather than a single episode, making them useful for custody evaluations, certain professional licensing requirements, and long-term sobriety verification. The markers can technically persist for six months or longer in untrimmed hair.
The Difference Between Sober and “Clean”
One of the most important distinctions is the gap between feeling sober and testing negative. Your liver may finish processing the alcohol in your bloodstream within a few hours, so you feel normal. But metabolic byproducts remain in your urine for days and in your hair for months. Feeling fine does not mean a test will come back clean, particularly with EtG urine screening.
This also works in reverse. A standard urine or blood test can miss alcohol consumed more than 24 hours ago, even if you drank heavily. That’s exactly why EtG testing was developed: to close that detection gap. If you’re unsure which test you’ll face, the safest assumption is the EtG window of 48 to 72 hours for urine, since it’s increasingly the default in clinical and legal settings.