Your liver clears alcohol at a roughly fixed rate of one standard drink per hour. A standard drink in the United States contains 14 grams of pure alcohol, which is the amount in a 12-ounce beer, a 5-ounce glass of wine, or a 1.5-ounce shot of liquor. So if you have three drinks, it will take approximately three hours for your blood alcohol level to return to zero, though several factors can stretch that timeline.
Why Your Liver Sets the Pace
Unlike most substances your body processes, alcohol is broken down at a nearly constant rate regardless of how much is in your system. Your liver handles the bulk of this work using two enzymes that act in sequence. The first converts alcohol into acetaldehyde, a toxic compound classified as a carcinogen. The second quickly converts acetaldehyde into acetate, a much less harmful substance that your body then breaks down into water and carbon dioxide.
This process has a hard ceiling. Research on ethanol pharmacokinetics puts the maximum elimination rate at about 8.5 grams per hour for a 154-pound (70 kg) person. That lines up closely with one standard drink (14 grams) taking roughly 90 minutes to two hours to fully clear, though many sources round this to “about one drink per hour” as a practical estimate. The key point is that drinking faster than your liver can work simply causes alcohol to accumulate in your bloodstream.
Factors That Speed Up or Slow Down Clearance
The one-drink-per-hour rule is an average. Your actual clearance time depends on several variables.
Body composition. Alcohol dissolves in water, not fat. Men typically carry more body water and less body fat than women of similar weight, giving alcohol a larger volume to dilute into. This means women generally reach higher blood alcohol concentrations from the same number of drinks and take relatively longer to clear them. Larger people of either sex also have more total body water, which works in their favor.
Food in your stomach. Eating before or while you drink slows the rate at which alcohol enters your bloodstream. Solid meals are more effective than liquid ones because they delay gastric emptying, keeping alcohol in the stomach longer where absorption is slower. Interestingly, food also appears to slightly increase the rate at which your liver eliminates alcohol, so eating gives you a double benefit: a lower peak blood alcohol level and somewhat faster clearance.
Liver health. A healthy liver handles alcohol efficiently, but chronic heavy drinking can overwhelm the detox pathway over time, reducing the liver’s ability to keep up. For people who have developed cirrhosis, even a single drink is considered toxic to the liver. Fatty liver disease, a common early stage of alcohol-related damage, also impairs processing speed.
How Long Alcohol Shows Up on Different Tests
Your blood alcohol level returning to zero doesn’t mean every trace of alcohol is gone. Different tests detect alcohol or its byproducts for very different windows.
- Breath tests: A breathalyzer can detect alcohol for up to 12 hours after your last drink, and in some cases up to 24 hours. The exact window depends on how much you drank and your personal metabolism.
- Urine tests (standard): A basic urine test picks up alcohol for roughly the same window as a breath test.
- Urine tests (EtG): These look for ethyl glucuronide, a metabolite your body produces when processing alcohol. After a few drinks, EtG can show up in urine for up to 48 hours. Heavier drinking can push that window to 72 hours or longer.
- Hair tests: Hair follicle tests detect EtG markers deposited in the hair shaft. Alcohol typically appears in hair for one to six months after drinking, though it takes several weeks after consumption before it shows up. Most results cover three to six months simply because people cut or trim their hair.
A Practical Timeline by Number of Drinks
Using the one-drink-per-hour baseline, here’s a rough estimate of how long it takes for your blood alcohol to reach zero after you stop drinking. These assume average body size and a healthy liver.
- 2 drinks: About 2 to 3 hours
- 4 drinks: About 4 to 6 hours
- 6 drinks: About 6 to 9 hours
- 10 drinks: About 10 to 15 hours
These ranges explain why someone who drinks heavily in the evening can still have a measurable blood alcohol level the next morning. If you finish your last drink at midnight after a night of heavy drinking, your BAC may not hit zero until well into the following afternoon.
Why Nothing Speeds Up the Process
Coffee, cold showers, exercise, and “detox” supplements do not make your liver work faster. Coffee can make you feel more alert, which may mask how impaired you actually are, but your blood alcohol level drops at the same fixed rate regardless. Drinking water helps with hydration and may ease hangover symptoms, but it doesn’t accelerate alcohol metabolism. The only thing that reliably clears alcohol from your system is time.