Alcohol is eliminated from your bloodstream at a fairly steady rate of about 20 mg/dL per hour, which works out to roughly one standard drink every 60 to 90 minutes for most people. But “how long it lasts” depends on what you mean: the buzz wearing off, the ability to pass a breathalyzer, or showing up on a drug test. Each of those has a very different timeline.
How Your Body Processes Alcohol
Your liver does the heavy lifting. An enzyme breaks alcohol into a toxic intermediate compound called acetaldehyde (a known carcinogen), and then a second enzyme quickly converts that into acetate, which your body breaks down further into water and carbon dioxide. Only about 2 to 5 percent of alcohol leaves through your breath, sweat, or urine. The rest goes through this liver pathway.
What makes alcohol unusual is that your liver can only process it at a fixed speed. Most substances clear faster when there’s more of them in your blood, but alcohol doesn’t work that way. The enzymes responsible get fully saturated even at moderate blood alcohol levels, so your body burns through the same amount per hour regardless of how much you drank. This means four drinks take roughly four times as long to clear as one drink. You can’t speed it up with coffee, food, or water after the fact.
The Standard Elimination Timeline
A standard drink in the United States contains 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. Your liver clears roughly one of these per hour, though there’s meaningful variation from person to person. Emergency department data shows the average clearance rate is about 20 mg/dL per hour, but the range is wide enough that some people clear alcohol nearly twice as fast as others, and some much more slowly.
To put that in practical terms: if you have four drinks over two hours and reach a blood alcohol concentration (BAC) of 0.08 percent (the legal limit in most U.S. states), it will take approximately four to five hours from your last drink for your BAC to drop back to zero. If you drink heavily and reach 0.15 percent, you’re looking at roughly seven to eight hours before alcohol fully clears your blood.
Detection Windows by Test Type
The type of test matters enormously. Here’s how long alcohol or its byproducts can be detected depending on what’s being measured:
- Blood test: Alcohol is detectable in blood for up to about 12 hours after your last drink.
- Breathalyzer: Roughly the same window as blood, since breath tests estimate your blood alcohol level. One quirk: residual alcohol in your mouth can falsely elevate results for up to 15 minutes after drinking, which is why officers are supposed to observe you for 15 minutes before administering the test.
- Standard urine test: Alcohol itself can show up in urine for 12 to 24 hours. But a more sensitive urine test looks for a metabolic byproduct that your body produces when processing alcohol. After light to moderate drinking, this byproduct is typically detectable for 24 to 48 hours. After heavy drinking, detection times extend dramatically, with a median of about 78 hours and some individuals testing positive for over 100 hours (more than four days).
- Hair test: Alcohol metabolites become trapped in the hair shaft as it grows. Since hair grows about 1 centimeter per month, a 3-centimeter sample covers roughly three months of drinking history. Longer samples can extend the window further, with metabolites remaining stable in hair up to about 12 centimeters in length.
Why It Takes Longer for Some People
Several factors determine how quickly your body eliminates alcohol and how high your BAC climbs in the first place.
Body Composition
Alcohol dissolves in water, not fat. Women generally have proportionally more body fat and less body water than men of the same weight, which means the same amount of alcohol gets distributed through a smaller volume of water. The result is a higher peak BAC from the same number of drinks, even after adjusting for body weight. Larger people of any sex tend to have more total body water, so the alcohol is more diluted.
Food in Your Stomach
Drinking on an empty stomach lets alcohol pass quickly into your small intestine, where it’s absorbed rapidly. Food slows gastric emptying, which spreads out absorption over a longer period. The peak BAC you reach can be substantially lower when you’ve eaten a full meal beforehand, even though the total amount of alcohol entering your system is the same. This doesn’t change how fast your liver eliminates alcohol, but it does affect how intoxicated you feel and how high your BAC climbs.
Drinking Frequency and Liver Health
Chronic heavy drinkers often develop a secondary metabolic pathway in the liver that can increase clearance speed somewhat. However, this comes with serious trade-offs, including liver damage that eventually slows metabolism down. People with liver disease process alcohol significantly more slowly because the organ responsible for elimination is compromised.
Genetics
The enzymes that break down alcohol vary in efficiency based on your genetic makeup. Some people of East Asian descent carry a variant of the second enzyme in the pathway that works more slowly, causing the toxic intermediate compound to build up. This produces the characteristic facial flushing and nausea some people experience after drinking. It also means their bodies take longer to fully process alcohol.
How Long Until You’re Actually Sober
Feeling sober and being sober are not the same thing. Your brain adjusts to alcohol’s effects over the course of a drinking session, so you may feel more functional than your BAC would suggest. Reaction time, judgment, and coordination can remain impaired even as the subjective feeling of drunkenness fades. Studies consistently show that people underestimate their own impairment on the descending side of the BAC curve, when alcohol levels are dropping but still elevated.
A rough guide: count the number of standard drinks you’ve had, then add one hour per drink from the time you stopped. If you had six drinks and stopped at midnight, your blood alcohol likely won’t reach zero until at least 6 a.m., and possibly later. If you drank over many hours, the math shifts because your liver was working the whole time, but the principle holds. The only thing that sobers you up is time.
Alcohol and Next-Day Testing
If you’re facing a workplace or legal alcohol test, the detection method matters more than anything. A standard breath or blood test the morning after moderate drinking (three or four drinks ending before midnight) will usually come back clean by mid-morning. But a urine test looking for the sensitive metabolic byproduct can catch moderate drinking 24 to 48 hours later, and heavy drinking for three to five days.
Hair testing operates on a completely different scale. It’s not designed to detect a single night of drinking but rather patterns of use over months. A single episode of light drinking may not produce enough of the metabolite to exceed testing thresholds, but regular drinking will.