Your liver processes roughly one standard drink per hour, so a single shot of liquor (1.5 ounces of 80-proof spirits) clears your bloodstream in about one to two hours. But “in your system” can mean different things depending on the type of test. A standard blood or breath test can pick up alcohol for up to 12 to 24 hours, while specialized urine tests detect a byproduct of alcohol for up to 80 hours, and hair tests can reveal drinking patterns from months ago.
How Your Body Processes Alcohol
Almost all the alcohol you drink is broken down in your liver by two enzymes that work in sequence. The first converts alcohol into a toxic intermediate compound, and the second converts that into a harmless substance your body can turn into water and carbon dioxide. This process runs at a fixed speed: about one standard drink per hour, or a blood alcohol reduction of roughly 0.015% per hour. You can’t speed it up with coffee, food, water, or exercise once alcohol is already in your bloodstream.
A standard drink in the United States contains 0.6 ounces (14 grams) of pure alcohol. For liquor at 40% alcohol by volume (80-proof), that’s a 1.5-ounce shot. Many cocktails contain two or three shots, which means a single mixed drink could count as two or three standard drinks and take two to three hours to fully metabolize.
Detection Windows by Test Type
How long alcohol shows up depends entirely on what’s being tested:
- Blood: Alcohol is detectable in blood for up to 12 hours after your last drink.
- Breath: A breathalyzer can detect alcohol for up to 24 hours, though for most people the window is closer to 12 hours.
- Standard urine test: A conventional urine screen picks up alcohol itself for roughly 12 to 24 hours.
- EtG urine test: This test looks for a metabolic byproduct rather than alcohol itself. It typically detects drinking within 24 to 72 hours, but after heavy consumption it can remain positive for up to 80 hours.
- Hair follicle test: Hair testing can reveal alcohol use from 1 to 6 months prior, sometimes longer if hair hasn’t been cut.
The EtG urine test is the one most commonly used in court-ordered monitoring, probation programs, and workplace situations where past-day drinking matters. Because it detects a byproduct rather than alcohol itself, even moderate drinking on a Friday night could produce a positive result on Monday morning.
What Affects How Fast You Metabolize Liquor
One drink per hour is the average, but several factors shift that number in either direction.
Body size and composition. People with more body weight and muscle mass generally distribute alcohol across a larger volume of water in their tissues, which means a lower peak blood alcohol level from the same number of drinks. Women, on average, absorb more alcohol and take longer to process it than men, partly because of differences in body fat percentage and water content. The CDC notes that women typically reach higher blood alcohol levels than men after drinking the same amount.
Food in your stomach. Eating before or while drinking slows the rate at which alcohol moves from your stomach into your small intestine, where most absorption happens. This delay gives your liver more time to begin processing alcohol before it all reaches your bloodstream, resulting in a lower and later peak blood alcohol level. A full meal won’t prevent intoxication, but it meaningfully reduces how high your blood alcohol climbs and how quickly it gets there.
Genetics. The enzymes that break down alcohol vary from person to person based on inherited gene variants. According to the National Institute on Alcohol Abuse and Alcoholism, alcohol metabolism is controlled by genetic factors, including variations in the specific enzymes responsible for breaking apart alcohol molecules. Some people of East Asian descent, for example, carry enzyme variants that cause the toxic intermediate compound to build up faster, leading to facial flushing and nausea.
Drinking patterns. Chronic heavy drinking temporarily speeds up one of the backup enzyme systems your liver uses. Research in Gastroenterology found that chronic drinkers cleared alcohol from their blood faster than non-drinkers during active consumption, but this elevated clearance rate returned to normal within about seven days of stopping. This does not mean heavy drinkers are less impaired; it means their livers are working harder, which comes with its own damage.
A Practical Timeline
If you have three shots of liquor (three standard drinks) over the course of an evening, your liver needs approximately three hours from your last drink to fully process the alcohol. But because absorption itself takes time, the math isn’t perfectly linear. A rough guide: take the number of standard drinks you consumed, subtract one for each hour since you started drinking, and you’ll have a ballpark of how many drinks’ worth of alcohol your body still needs to clear.
For someone who had four drinks ending at midnight, blood alcohol would likely reach zero sometime between 3 and 5 a.m. A breathalyzer could still read positive into the next morning. And an EtG urine test could flag that drinking episode for two to three days afterward.
Keep in mind that feeling sober and being at zero blood alcohol are not the same thing. Impairment in reaction time and judgment can linger even as your blood alcohol drops, especially after heavy drinking. The only reliable way to know alcohol has fully left your system is to allow enough time, roughly one hour per standard drink consumed, measured from when you stopped drinking.