Your body eliminates alcohol at a roughly constant rate of about one standard drink per hour, though the actual range varies. Someone with a blood alcohol concentration (BAC) of 0.10 (legally impaired in every U.S. state) would take anywhere from 5 to 10 hours to reach 0.00. The exact timeline depends on how much you drank, your body size, your biological sex, and whether you ate beforehand.
How Your Body Processes Alcohol
Almost all the alcohol you drink is broken down in the liver through a two-step process. First, an enzyme converts alcohol into a toxic intermediate compound called acetaldehyde. Then a second enzyme quickly converts acetaldehyde into a harmless substance your body can use for energy or excrete.
The key detail is that the main enzyme responsible for the first step has a limit. Once you’ve had more than a small amount of alcohol, that enzyme is working at full capacity and can’t go any faster no matter how much alcohol is in your blood. This is why alcohol disappears from your system at a steady, predictable rate rather than clearing faster when levels are high. You can’t speed it up with coffee, water, food, or sleep. Your liver simply works through the backlog at its own pace.
The One-Drink-Per-Hour Rule
A standard drink in the United States contains about 14 grams of pure alcohol. That’s one 12-ounce beer, one 5-ounce glass of wine, or one 1.5-ounce shot of liquor. Most people metabolize roughly this amount per hour, though individual rates range from slightly below to slightly above that figure.
As a practical estimate: if you stop drinking at midnight with a BAC of 0.08 (the legal limit for driving), you’d likely reach 0.00 somewhere between 4 and 8 hours later. If you had a heavier night and hit a BAC of 0.15, you could still have alcohol in your blood well into the next afternoon. People routinely underestimate how long this takes, especially after a night of heavy drinking where BAC peaks higher than they realize.
Why Metabolism Varies Between People
Body weight plays a straightforward role: a larger person has more blood volume, so the same number of drinks produces a lower BAC and clears faster in absolute terms. But body composition matters too. Alcohol distributes into water, not fat, so two people at the same weight will process alcohol differently if one carries more body fat.
Biological sex creates significant differences. Research in the American Journal of Physiology found that females have roughly 70% higher activity of the primary alcohol-processing enzyme in the liver compared to males. This sounds like it would help women clear alcohol faster, but the picture is more complicated. Women typically have lower body water content and smaller body size, which means higher BAC from the same amount of alcohol. The net result is that women generally feel the effects of alcohol more intensely, even though their liver enzyme activity is higher.
Genetics also plays a role. Some people, particularly those of East Asian descent, carry a variation in the second-step enzyme that makes it less effective. This causes acetaldehyde to build up, producing facial flushing, nausea, and rapid heartbeat. It doesn’t necessarily mean alcohol leaves the system slower overall, but it changes how the body experiences the process.
How Food Changes the Timeline
Eating before or while drinking doesn’t change how fast your liver works, but it does change how quickly alcohol enters your bloodstream in the first place. Alcohol absorbs much faster on an empty stomach than a full one. Solid meals slow this absorption more than liquid meals, mainly because food keeps alcohol in the stomach longer before it passes into the small intestine where most absorption happens.
Some research suggests that food may also slightly increase the overall rate of alcohol elimination, though the more noticeable effect is on absorption. In practical terms, drinking on a full stomach means a lower peak BAC and a shorter total window before you’re back to zero. Drinking on an empty stomach means a higher, faster spike and a longer wait.
Detection Windows by Test Type
If your concern is a specific test rather than just feeling sober, the detection window depends entirely on what’s being tested.
- Breath test: A breathalyzer can detect alcohol for up to 12 hours after your last drink, and in some cases up to 24 hours. This is the test used in roadside stops and workplace screening.
- Blood test: A standard blood alcohol test can detect alcohol for roughly 12 hours after your last drink.
- Urine test (standard): Alcohol itself clears from urine within a similar timeframe as blood, roughly 12 hours.
- Urine test (EtG): This specialized test looks for a byproduct your body creates when processing alcohol, not the alcohol itself. After a few drinks, this marker can show up in urine for 48 hours. After heavier drinking, it can persist for 72 hours or longer. EtG tests are commonly used in court-ordered monitoring and treatment programs.
- Hair test: Hair follicle testing can detect alcohol use from 1 to 6 months after drinking. It takes several weeks for evidence of a drinking episode to appear in a hair sample, so it can’t detect very recent use. Most results cover a 3 to 6 month window simply because people cut their hair.
Why You Might Still Feel Off at 0.00 BAC
Reaching a BAC of 0.00 doesn’t mean you feel normal. Hangover symptoms, including headache, nausea, fatigue, and difficulty concentrating, are partly caused by the toxic intermediate compound produced during alcohol breakdown, along with dehydration and disrupted sleep. These effects can persist for 24 hours or more after your last drink, well beyond when the alcohol itself has cleared. Your reflexes and cognitive performance can also remain impaired during a hangover, even though a breathalyzer would read zero.
For someone who had four or five drinks over the course of an evening and stopped at midnight, a reasonable expectation is that alcohol itself clears by early to mid-morning, but full recovery of alertness and coordination may take until the afternoon.