Alcohol leaves your bloodstream at a fairly predictable rate: about one standard drink per hour. More precisely, your liver clears alcohol at roughly 0.015% blood alcohol concentration (BAC) per hour, which means a BAC of 0.08% (the legal driving limit in the U.S.) takes about five and a half hours to reach zero. But “how long alcohol lasts” depends on what you mean: how long you feel its effects, how long it takes to fully leave your body, and how long it shows up on different tests are all different timelines.
How Fast Your Body Processes Alcohol
Your liver does nearly all the work. It breaks down alcohol using enzymes at a fixed, linear rate, meaning it clears the same amount per hour regardless of how much you drank. The central estimate is about 15 milligrams per deciliter of blood per hour, though individuals range from 10 to 20 mg/dL/h depending on genetics, body composition, and drinking history.
In practical terms, one U.S. standard drink (14 grams of pure alcohol, roughly a 12-ounce beer, 5-ounce glass of wine, or 1.5-ounce shot of liquor) raises most people’s BAC by about 0.02% to 0.03%. At the average elimination rate, that single drink takes about one to two hours to fully clear. Three drinks might take four to five hours. A heavy night of six or seven drinks could keep alcohol circulating in your blood for eight hours or more after your last sip.
What Affects How Long It Stays
Several factors shift this timeline in either direction. Your body size matters: a smaller person reaches a higher BAC from the same amount of alcohol, so it takes longer to come back down. Women generally metabolize alcohol more slowly than men, partly because of differences in body water content and enzyme activity. Food in your stomach slows absorption, which can spread out the effects but doesn’t change how quickly your liver works once alcohol reaches the bloodstream.
Genetics play a significant role. Variations in the two key enzymes your liver uses to process alcohol differ across individuals and populations. People who drink heavily over time may develop a secondary metabolic pathway that kicks in during high-volume consumption, but this doesn’t meaningfully speed up clearance for moderate drinkers. Certain medications can also interfere with alcohol metabolism, resulting in higher BAC levels that last longer than expected.
How Long Alcohol Shows Up on Tests
Standard breath and blood tests detect alcohol only while it’s actively in your system. A breathalyzer picks up alcohol for roughly 12 to 24 hours after heavy drinking, depending on how much you consumed. Blood tests have a similar window.
Urine testing extends that window significantly. A standard urine alcohol test can detect alcohol for about 12 to 24 hours. But a more sensitive urine test measures a metabolite called EtG (ethyl glucuronide), which your body produces as it breaks down alcohol. After a few drinks, EtG can show up in urine for up to 48 hours. Heavier drinking pushes that to 72 hours or longer.
Hair follicle tests have the longest detection window. Alcohol markers typically appear in hair strands for one to six months, though most people cut or trim their hair often enough that three to six months is the practical limit.
When Effects Wear Off vs. When You’re Sober
The buzz from alcohol peaks about 30 to 90 minutes after your last drink, depending on how fast you drank and whether you ate beforehand. But feeling “normal” again doesn’t mean your BAC has hit zero. Residual impairment in reaction time, judgment, and coordination can persist well after the obvious effects fade. This is why people sometimes feel fine to drive in the morning and still blow over the legal limit.
Nothing speeds up the process. Coffee, cold showers, exercise, and water are all persistent myths. They might make you feel more alert, but your BAC drops at the same fixed rate regardless. Time is the only thing that actually works.
Hangover Timeline
Hangover symptoms are a separate clock that starts ticking as alcohol leaves. They peak right around the time your BAC returns to zero, which is why you often feel worst the morning after rather than while you’re still drinking. The headache, nausea, fatigue, and sensitivity to light are driven by dehydration, inflammation, and irritation of your stomach lining.
A mild hangover from a few drinks may clear up in a few hours. A severe hangover after heavy drinking can last a full 24 hours or longer, according to the National Institute on Alcohol Abuse and Alcoholism. Some people report lingering fatigue or brain fog for up to two days after particularly heavy episodes, though this varies widely.
Quick Reference by Amount
- 1 standard drink: roughly 1 to 2 hours to clear from blood
- 3 drinks: roughly 4 to 5 hours
- 5 drinks: roughly 6 to 8 hours
- 8+ drinks: 10 hours or more, potentially into the next afternoon
- EtG urine detection: up to 48 hours (moderate drinking) or 72+ hours (heavy drinking)
- Hair test detection: up to 3 to 6 months
These are averages for a mid-sized adult. Your personal clearance rate depends on the factors outlined above, and there’s no reliable way to calculate your exact BAC at home. If you need to be completely sober for driving, work, or a test, the safest approach is to give yourself more time than you think you need.