Your liver clears alcohol at a steady rate of about one standard drink per hour. That means if you have three drinks, it takes roughly three hours for your blood alcohol level to return to zero. But “in your system” can mean different things depending on what’s being tested, and some methods can detect traces of alcohol days or even months after your last drink.
What Counts as One Drink
In the United States, one standard drink 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 real-world pours exceed these amounts. A strong IPA in a pint glass or a generous wine pour could easily count as 1.5 to 2 standard drinks, which changes the math on how long your body needs to process it.
How Your Body Breaks Down Alcohol
Most alcohol is processed in the liver using an enzyme that converts ethanol into a toxic compound called acetaldehyde, a known carcinogen. A second enzyme quickly breaks acetaldehyde down into acetate, a relatively harmless substance your body can use for energy. Acetaldehyde is short-lived, usually existing only briefly before being converted, but it’s responsible for much of the cellular damage linked to heavy drinking.
Your liver handles this work at a fixed pace. Nothing speeds it up. Coffee, cold showers, food, and water may help you feel more alert, but they don’t change how fast alcohol leaves your bloodstream. Time is the only thing that clears it.
Detection Windows by Test Type
How long alcohol shows up depends entirely on what kind of test is used:
- Blood: up to 12 hours
- Breath: 12 to 24 hours
- Saliva: up to 12 hours
- Standard urine test: 12 to 24 hours, or 72 hours or more after heavier drinking
- EtG urine test: up to 48 hours after a few drinks, and sometimes 72 hours or longer after heavier use
- Hair follicle: up to 90 days
The EtG test deserves extra attention because it’s commonly used in court-ordered monitoring, workplace programs, and treatment settings. It doesn’t detect alcohol itself. Instead, it picks up a byproduct your body creates when processing alcohol. That’s why its detection window stretches so much further than a standard urine screen.
How Long Until Your BAC Hits Zero
Your blood alcohol concentration (BAC) drops at a roughly constant rate, but the starting point varies by body size and sex. After two standard drinks, men typically reach a zero BAC in 1 to 2 hours, while women need 1.5 to 3 hours. The difference grows with more drinks. After five or six drinks consumed over an evening, you could still have a measurable BAC well into the next morning.
A common mistake is assuming you’re fine to drive after sleeping for a few hours. If you stopped drinking at midnight after having six drinks, your liver still needs until roughly 6 a.m. to fully clear the alcohol. Sleep doesn’t accelerate the process.
Why It Takes Longer for Some People
Several factors change how quickly alcohol accumulates in your blood and how fast your body clears it. Body size and weight matter because alcohol distributes through body water. A smaller person reaches a higher BAC from the same number of drinks. Body composition plays a role too: fat tissue doesn’t absorb alcohol as well as muscle, so more body fat means less volume for alcohol to dilute into.
Biological sex is one of the biggest variables. Women generally absorb more alcohol and take longer to process it than men, even when controlling for body weight. This is partly due to differences in body composition, with women on average carrying more body fat and less water per pound. The result is that women typically reach higher blood alcohol levels after the same number of drinks.
Other factors include how much you’ve eaten (food slows absorption but doesn’t prevent it), how quickly you drank, and whether your liver is healthy. Chronic heavy drinking can impair liver function over time, further slowing the clearance rate.
Alcohol and Breast Milk
Alcohol passes freely into breast milk at roughly the same concentration as your blood. For each standard drink consumed, alcohol can generally be detected in breast milk for about 2 to 3 hours. The CDC notes that waiting at least 2 hours per drink before nursing allows alcohol levels in breast milk to drop. So two drinks would mean waiting about 4 hours. Pumping and discarding milk doesn’t clear the alcohol faster; levels in breast milk decline only as levels in your blood decline.
Practical Timelines
If you’re trying to estimate when alcohol will be fully out of your system, here’s a straightforward way to think about it. Count the number of standard drinks you had (being honest about pour sizes), then allow roughly one hour per drink from the time you stopped. That gives you a ballpark for when your blood alcohol should reach zero.
For testing purposes, the timeline is longer. A standard urine test could catch you the next day. An EtG test could flag drinking from two to three days earlier. And a hair test can reveal patterns of alcohol use going back three months. If you’re subject to any of these, the one-drink-per-hour rule for blood clearance won’t tell the whole story.