Your liver clears alcohol at a roughly fixed rate of about one standard drink per hour. So if you have three drinks, it takes approximately three hours for your blood alcohol level to return to zero. But “leaving your system” depends on what you mean: alcohol itself disappears from your blood within hours, while byproducts of alcohol metabolism can linger in your urine for days and in your hair for months.
What Counts as One Drink
A standard drink in the United States contains 0.6 ounces (14 grams) of pure alcohol. That works out to about 12 ounces of regular beer, 5 ounces of wine, or 1.5 ounces of distilled spirits. These are smaller pours than many people realize, especially at bars or restaurants where wine glasses are filled generously and craft beers run higher in alcohol content. If your “one glass of wine” is actually closer to 8 ounces, your liver treats it as roughly 1.5 standard drinks.
How Your Liver Processes Alcohol
Almost all the alcohol you drink is broken down in the liver through a two-step process. First, an enzyme converts ethanol into a toxic compound called acetaldehyde, which is a known carcinogen. Your body doesn’t hold onto acetaldehyde for long. A second enzyme quickly converts it into acetate, a far less harmful substance that eventually breaks down into water and carbon dioxide, which your body eliminates easily.
This process runs at a near-constant speed regardless of how much you drank. Your liver simply cannot be rushed. Coffee, cold showers, food, and water do not accelerate the breakdown. Time is the only thing that clears alcohol from your blood.
Rough Timeline by Number of Drinks
At one standard drink per hour, you can estimate when your blood alcohol concentration (BAC) will reach zero:
- 2 drinks: approximately 2 hours
- 4 drinks: approximately 4 hours
- 6 drinks: approximately 6 hours
- 10 drinks: approximately 10 hours
These are ballpark figures. Individual variation can shift your actual clearance time by 30 minutes or more in either direction per drink. And because your BAC keeps rising for a short time after your last sip (while alcohol is still being absorbed from your stomach), the clock doesn’t start the moment you put your glass down.
For context, the legal driving limit is 0.08 g/dL in every state except Utah, which lowered its limit to 0.05 g/dL in 2018. Drivers under 21 face limits of 0.02 g/dL or lower nationwide. Even a single drink can push a smaller person above that threshold, so the one-drink-per-hour rule is not a safe guide for deciding when to drive.
Why It Takes Longer for Some People
The one-drink-per-hour average masks real biological differences. Women generally reach higher blood alcohol levels than men after drinking the same amount, even at the same body weight. The main reason is body composition: women typically carry a lower proportion of body water, and since alcohol dissolves in water, the same amount of ethanol ends up more concentrated in a smaller water volume. Research also shows that women have lower alcohol elimination rates measured in grams per hour, likely because of differences in lean body mass and liver size.
Body weight matters on its own, too. A 130-pound person will hit a higher BAC from the same number of drinks than a 200-pound person, simply because there’s less total body water to dilute the alcohol. Age plays a smaller role, but older adults may notice alcohol hits harder as body water percentage decreases over time. Eating before or while you drink slows absorption, which lowers your peak BAC, but it doesn’t change how fast your liver works once the alcohol is in your bloodstream.
Detection Windows by Test Type
If you’re wondering about alcohol showing up on a test, the answer depends entirely on what kind of test it is. Each one measures something different and has its own detection window.
Breath tests detect alcohol that’s actively circulating in your blood and being exhaled through your lungs. A breathalyzer will generally show alcohol for as long as your BAC is above zero, which means roughly one hour per standard drink consumed.
Blood tests work on a similar timeline. They measure current BAC and are only useful within several hours of drinking. Once your liver finishes processing the alcohol, a blood test comes back clean.
Standard urine tests also detect alcohol itself and typically show positive results for a window similar to blood, though urine concentrations can lag slightly behind blood levels.
EtG urine tests are a different story. These look not for alcohol itself but for a metabolic byproduct called ethyl glucuronide. After a few drinks, EtG can show up in urine for up to 48 hours. After heavier drinking, it can remain detectable for 72 hours or sometimes longer. This is the test commonly used in court-ordered monitoring, workplace programs, and treatment settings precisely because of its longer detection window.
Hair follicle tests have the longest reach. Alcohol metabolites get incorporated into hair as it grows, creating a record of consumption that can be detected for one to six months. These tests are not looking for a single night of drinking; they’re designed to identify patterns of use over time.
What This Means in Practice
If you had four drinks finishing around midnight, your BAC likely won’t reach zero until roughly 4 a.m., and possibly later depending on your size and sex. If you had a heavier night of eight or ten drinks ending at midnight, you could still have alcohol in your blood well into the next morning. Many people are surprised to learn they can still be legally impaired at breakfast.
For an EtG urine test, that same heavy night of drinking could produce a positive result two or even three days later, even though you feel completely sober and your BAC is long gone. And if you’re facing a hair test, any significant drinking in the past several months is potentially on the record.
The simplest rule: your liver needs about one hour per standard drink to clear alcohol from your blood. Everything else, from body size to biological sex to the type of test, adjusts that baseline in ways that almost always make it take longer than people expect.