Your body clears alcohol at a fairly fixed rate of about one standard drink per hour. That means a single beer or glass of wine is typically out of your bloodstream in roughly 60 to 90 minutes, while a night of four or five drinks could take five hours or more to fully metabolize. But “how long alcohol stays in your system” depends on what you mean by “your system,” because traces of alcohol linger in urine, hair, and other tissues far longer than in your blood.
How Your Body Processes Alcohol
When you drink, your liver does the heavy lifting. It converts alcohol into a toxic intermediate compound called acetaldehyde (the chemical partly responsible for hangovers), then quickly breaks that down into acetate, which your body uses for energy or excretes. For a person weighing about 155 pounds, the liver can process roughly 7 grams of alcohol per hour. That’s about the amount in one standard drink: a 12-ounce beer, a 5-ounce glass of wine, or a 1.5-ounce shot of liquor.
This process runs at a nearly constant speed. Unlike many other substances, alcohol doesn’t clear faster just because there’s more of it in your blood. Your liver works through the queue at its own pace, so drinking more simply means waiting longer. A blood alcohol concentration (BAC) of 0.08, the legal driving limit in most U.S. states, takes roughly four to five hours to drop back to zero from the time you stop drinking.
Detection Windows by Test Type
Different tests pick up alcohol, or its byproducts, over very different timeframes:
- Blood test: Detects alcohol for up to 12 hours after your last drink.
- Breathalyzer: Can register alcohol on your breath for up to 24 hours, though most moderate drinkers will test clean well before that.
- Standard urine test: Picks up alcohol itself for roughly 12 to 24 hours.
- EtG urine test: This more sensitive test looks for a specific metabolic byproduct your liver produces when it processes alcohol. At common testing thresholds, it can detect heavy drinking for up to five days. At higher cutoff levels, it’s mostly useful for detecting heavy drinking within the previous day.
- Hair follicle test: Can reveal alcohol use for up to 90 days, since traces get embedded in hair as it grows.
If you’re concerned about workplace or legal testing, the type of test matters enormously. A standard breath or blood screen gives a relatively short window, while an EtG urine panel or hair test can look much further back.
Why It Takes Longer for Some People
The one-drink-per-hour figure is an average, and several factors shift it in either direction.
Biological sex. Women generally reach higher blood alcohol levels than men after drinking the same amount, even at similar body weights. The primary reason is that women have lower activity of a key stomach enzyme involved in breaking down alcohol before it reaches the bloodstream. Women also have a slightly smaller volume of body water to dilute alcohol into, and their stomachs empty alcohol more slowly. These differences combined mean alcohol hits harder and lingers longer.
Body size and composition. A larger person has more blood volume and body water, so the same number of drinks produces a lower BAC. Muscle tissue holds more water than fat, so two people at the same weight can have different BACs depending on their body composition.
Food in your stomach. Eating before or while you drink slows the absorption of alcohol into your bloodstream and lowers your peak BAC. Interestingly, though, research shows the total time to clear alcohol completely doesn’t change much. In one controlled study, the time to reach zero was virtually identical (about five hours) whether participants drank on a full or empty stomach. Food smooths out the curve but doesn’t shorten the ride.
Liver health. You might assume that someone with liver disease would process alcohol far more slowly, but research on patients with cirrhosis found that the liver’s maximum processing speed wasn’t significantly different from that of healthy subjects. The liver has substantial reserve capacity, though this doesn’t mean drinking is safe with liver disease. It simply means the metabolism rate itself remains surprisingly stable until the organ is severely compromised.
Why Coffee, Showers, and Exercise Don’t Help
The idea that you can sober up faster with a cold shower, a strong coffee, or a workout is persistent and wrong. Controlled studies have shown that adding caffeine (including energy drinks) to alcohol does not change breath alcohol concentration at all. It also doesn’t improve alcohol-impaired driving performance or reaction time. Caffeine may make you feel more alert, but your BAC and your actual impairment remain exactly the same. Your liver sets the pace, and nothing you do from the outside speeds it up.
The only thing that reliably lowers your BAC is time.
Practical Timelines for Common Scenarios
To give you a rough sense of how long alcohol stays active in your body, here are some general estimates based on the average metabolism rate. These assume you stopped drinking at a specific point and your liver is processing about one standard drink per hour.
- 1 to 2 drinks: Blood alcohol typically clears within 1 to 3 hours.
- 3 to 4 drinks: Expect 3 to 5 hours before your BAC returns to zero.
- 5 to 6 drinks: You’re looking at 5 to 7 hours, meaning a night of heavy drinking that ends at midnight could leave you over the legal limit well into the next morning.
- 8 or more drinks: Full clearance could take 8 to 12 hours or longer. Many people are still impaired when they drive to work the morning after a big night out.
These numbers are rough guides, not guarantees. Your actual clearance depends on the factors above, including your weight, sex, and whether you ate. The safest approach after heavy drinking is to wait longer than you think you need to, because people consistently underestimate how long alcohol remains in their system.
How Breathalyzers Estimate Your BAC
Breathalyzers don’t measure blood alcohol directly. They measure the concentration of alcohol in the air from your lungs and then use a mathematical ratio to estimate your BAC. The standard conversion assumes that 1 milliliter of blood contains 2,100 times more alcohol than 1 milliliter of deep lung air. Some jurisdictions use a slightly different ratio of 2,300:1, which more closely matches experimental data. This means breathalyzer readings are estimates, and individual variation in lung function, body temperature, and breathing patterns can introduce small errors in either direction.