For most people, the body clears alcohol at a rate that brings blood alcohol concentration (BAC) down by about 0.015 per hour. That means if you reach a BAC of 0.08 (the legal driving limit in most U.S. states), it will take roughly 5 to 6 hours to get back to zero. A higher BAC of 0.10 could take anywhere from 5 to 10 hours, depending on your individual metabolism.
But “leaving your system” means different things depending on context. Alcohol itself may be gone from your blood within hours, while certain byproducts can show up on specialized tests for days or even months.
How Your Body Processes Alcohol
Your liver does the heavy lifting. Enzymes in the liver break alcohol down into a toxic intermediate compound called acetaldehyde, then quickly convert that into harmless acetate, which your body uses for energy or excretes. This process is essentially fixed-rate: your liver can only work so fast, no matter how much you drink. Think of it like a turnstile that lets one person through at a time. Drinking more doesn’t speed up the line; it just makes it longer.
A standard drink in the United States contains 0.6 ounces (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. Each standard drink adds roughly 0.02 to 0.03 to your BAC (depending on your size and sex), and your body removes about 0.010 to 0.020 per hour. So a single drink typically clears in about 1.5 to 2 hours, while four drinks might take 6 to 8 hours or more.
Factors That Speed Up or Slow Down Clearance
Several things shift the timeline in either direction.
Body weight and composition. A larger person has more blood volume, which dilutes alcohol and produces a lower peak BAC from the same number of drinks. A 200-pound person will reach a lower BAC than a 120-pound person after the same two beers, and will clear that alcohol sooner simply because there’s less to process per unit of blood.
Biological sex. Women generally reach higher BACs than men from the same amount of alcohol, even at the same body weight. This is partly because women tend to have a higher proportion of body fat (which doesn’t absorb alcohol) and lower levels of a stomach enzyme that breaks down some alcohol before it enters the bloodstream.
Food in your stomach. Eating before or while you drink makes a significant difference. In one study, people who drank on a full stomach absorbed only about 66 to 72% of the alcohol compared to those who drank while fasting, and their peak BAC was about 30% lower. Food slows the rate at which alcohol moves from your stomach into your small intestine, where most absorption happens. This doesn’t change how fast your liver works, but it means your BAC peaks lower, so there’s less to clear overall.
Genetics. The enzymes that break down alcohol vary from person to person. Some people naturally produce more efficient versions of these enzymes. Others, particularly many people of East Asian descent, carry a genetic variant that makes them accumulate acetaldehyde faster than they can clear it, causing facial flushing, nausea, and rapid heartbeat after even small amounts of alcohol.
Drinking history. Chronic heavy drinkers develop a degree of metabolic tolerance. Their bodies activate backup enzyme pathways that kick in during heavy consumption, and research shows their BAC drops faster after drinking compared to light drinkers. However, this faster metabolism doesn’t translate to less impairment on demanding tasks. Heavy drinkers simply feel less drunk while being just as impaired.
Detection Windows by Test Type
If you’re asking this question because of a test, the type of test matters enormously. Alcohol itself disappears from your body relatively quickly, but your body produces trace byproducts that linger much longer.
Breath test (breathalyzer): Detects alcohol for roughly 12 to 24 hours after your last drink, depending on how much you consumed. A breathalyzer measures alcohol that’s still in your bloodstream and being exchanged through your lungs, so once your BAC hits zero, you’ll pass.
Standard blood test: Similar to a breathalyzer. Alcohol is typically undetectable in blood within 12 hours of moderate drinking, though heavy drinking can extend that.
Standard urine test: Alcohol can be detected in urine for roughly 12 to 24 hours with a conventional test. But urine tests aren’t always conventional.
EtG urine test: This is the one that catches people off guard. EtG (ethyl glucuronide) is a byproduct your body creates when processing alcohol, and it sticks around long after the alcohol itself is gone. After a few drinks, EtG can show up in urine for up to 48 hours. After heavier drinking, it can be detectable for 72 hours or longer. EtG represents less than 0.5% of the alcohol you consumed, but it’s stable and persistent, which is exactly why testing programs use it.
Hair follicle test: This is the longest detection window by far. Alcohol markers can appear in a hair strand test for 1 to 6 months, giving a picture of drinking patterns over time rather than a single episode. While blood, urine, and breath tests capture a snapshot of hours or days, a hair test looks at months of use.
A Rough Timeline for Common Scenarios
Here’s what clearance looks like in practical terms, assuming you stop drinking and your body is processing alcohol at an average rate of 0.015 BAC per hour:
- 1 to 2 standard drinks: Alcohol likely cleared from blood in 2 to 3 hours. You’d pass a breathalyzer within that window.
- 3 to 4 standard drinks: Expect 4 to 6 hours for your BAC to return to zero.
- 5 to 6 standard drinks: Could take 7 to 10 hours. If you stop drinking at midnight, you may still have a measurable BAC the next morning.
- Heavy night out (8+ drinks): Clearance can take 12 hours or more. Many people underestimate this and drive the next morning while still technically over the legal limit.
These are estimates for an average-sized adult. Your actual clearance time could be shorter or longer depending on the factors above.
Alcohol and Breastfeeding
Alcohol passes freely into breast milk at roughly the same concentration as your blood. It also leaves breast milk at the same rate it leaves your blood, so “pumping and dumping” doesn’t speed things up. You simply have to wait.
For a 140-pound woman, one standard drink takes about 2 hours and 19 minutes to fully clear from breast milk. Two drinks take about 4 hours and 38 minutes. Three drinks take nearly 7 hours. A lighter woman clears alcohol more slowly: at 120 pounds, one drink takes about 2 hours and 30 minutes, and three drinks take 7 hours and 30 minutes. A heavier woman at 180 pounds clears one drink in about 2 hours, and three drinks in about 6 hours and 5 minutes. Each additional drink adds roughly 2 to 2.5 hours to the total clearance time.
Why You Still Feel Rough After Alcohol Clears
Your BAC can hit zero and you can still feel terrible. Hangovers aren’t caused by alcohol still being in your system. They’re largely driven by dehydration, inflammation, disrupted sleep, and irritation of your stomach lining. The toxic intermediate your liver produces during metabolism, acetaldehyde, is normally broken down so efficiently that it stays at extremely low levels in your blood (over 1,000 times lower than the alcohol itself). But the downstream effects of processing alcohol, including immune system activation and electrolyte imbalances, persist well after the alcohol is gone.
There’s no way to speed up alcohol metabolism. Coffee, cold showers, and exercise might make you feel more alert, but your liver still processes alcohol at the same fixed rate. The only thing that actually works is time.