Your body eliminates alcohol at a steady rate of about one standard drink per hour, which translates to a blood alcohol concentration (BAC) drop of roughly 0.015 to 0.020 per hour. That means if you reach a BAC of 0.08 (the legal limit in most states), it takes four to five hours from your last drink to return to zero. But the real answer depends on how much you drank, your body size, and several other factors that can stretch that timeline significantly.
How Fast Your Body Processes Alcohol
Your liver does nearly all the work of breaking down alcohol, and it operates at a fixed pace. No amount of coffee, water, food, or fresh air speeds it up once alcohol is in your bloodstream. One standard drink per hour is the average, though the actual clearance rate varies between individuals.
A “standard drink” in the United States contains 0.6 ounces (14 grams) of pure alcohol. That equals:
- Beer: 12 ounces at 5% alcohol
- Wine: 5 ounces at 12% alcohol
- Liquor: 1.5 ounces (one shot) at 40% alcohol
- Malt liquor: 8 ounces at 7% alcohol
Many real-world drinks exceed these sizes. A pint of craft beer at 7% alcohol is closer to two standard drinks. A generous restaurant pour of wine can easily be 8 ounces. If you’re estimating when you’ll be safe to drive, counting actual standard drinks rather than “number of glasses” gives a much more accurate picture.
Rough Timelines by Number of Drinks
Because BAC drops at about 0.015 to 0.020 per hour, you can estimate how long it takes to reach zero based on your peak BAC. For an average-sized person, these are approximate clearance times from the point you stop drinking:
- 2 standard drinks: roughly 2 to 3 hours
- 4 standard drinks: roughly 4 to 5 hours
- 6 standard drinks: roughly 7 to 8 hours
- 8 standard drinks: roughly 9 to 11 hours
- 10+ standard drinks: 12 hours or more
These timelines assume you’ve stopped drinking and your BAC has already peaked. Alcohol continues to absorb into your bloodstream for 30 to 90 minutes after your last drink, so the clock doesn’t truly start the moment you put down the glass.
What Affects How Quickly You Clear Alcohol
Several biological factors change how high your BAC climbs and how long it stays elevated.
Body size and composition. A smaller person reaches a higher BAC from the same number of drinks than a larger person. Body composition matters too: alcohol distributes through water in the body, so people with more muscle mass (which holds more water) dilute alcohol more effectively than people with higher body fat percentages.
Biological sex. Women generally absorb more alcohol and take longer to process it than men, even at the same body weight. The CDC notes this is partly because women tend to have less body water and more body fat relative to their size. After the same number of drinks, women typically have higher BAC levels.
Food in your stomach. Eating before or while drinking slows the rate alcohol reaches your small intestine, where most absorption happens. Research from Johns Hopkins University found that having food in your stomach increases the rate of alcohol elimination from the bloodstream by 25 to 45%. Drinking on an empty stomach does the opposite, letting alcohol hit your bloodstream fast and pushing your peak BAC higher.
Liver health. Anyone with liver damage or liver disease processes alcohol more slowly. Certain medications can also interfere with alcohol metabolism.
Legal BAC Limits for Driving
In most U.S. states, the legal limit is a BAC of 0.08%. But that number doesn’t tell the whole story. Some states, including Colorado and Utah, enforce a lower threshold of 0.05% for a charge of driving while ability impaired (DWAI). You don’t need to be at 0.08 to face legal consequences.
Drivers under 21 face much stricter rules. Texas, for example, enforces a zero tolerance law that makes it illegal for any minor to operate a vehicle with any detectable amount of alcohol. Many other states set the underage limit at 0.02%, which a single drink can easily exceed. Commercial driver’s license holders also face a lower legal limit of 0.04% in most states.
Being below the legal limit doesn’t mean you’re unimpaired. Reaction time and judgment begin to decline well before 0.08%. A BAC of 0.02 to 0.04 already reduces your ability to track moving objects and divide attention between tasks.
The Morning After Problem
One of the most underestimated risks is driving the morning after a night of heavy drinking. If you had eight or more drinks and stopped at midnight, your BAC may not reach zero until late morning. Even if it technically hits zero, you’re not necessarily safe behind the wheel.
Research on drivers the morning after drinking found something concerning: even when BAC had returned to legal levels, drivers traveled at higher maximum speeds, spent more time over the speed limit, and showed greater variation in speed. Their visual attention appeared normal, but their behavior on the road was measurably more dangerous.
This happens partly because of how the brain recovers from alcohol. As BAC falls, motor coordination bounces back faster than cognitive function. You may feel physically fine and perceive that your reflexes are normal while your decision-making and impulse control are still impaired. Researchers describe this as the reason people feel confident enough to drive while still being functionally compromised. Hangover symptoms, which begin as BAC approaches zero, layer fatigue, dehydration, and slowed processing on top of any residual impairment.
How Long Alcohol Shows Up on Tests
If you’re wondering about detection for legal or employment testing, alcohol shows up for different lengths of time depending on the test.
A standard breathalyzer detects alcohol for roughly 12 to 24 hours after heavy drinking, though for moderate drinking (two to three drinks) it typically clears within several hours. Blood tests have a similar detection window. Both of these methods measure active alcohol in your system.
Urine testing extends the window considerably. A standard urine test catches alcohol for about 12 to 24 hours. But a specialized urine test called EtG (which detects a byproduct of alcohol metabolism rather than alcohol itself) can find evidence of drinking up to 48 hours later. After heavier drinking, EtG can remain positive for 72 hours or longer. This test is commonly used in probation, court-ordered monitoring, and workplace testing programs.
Practical Guidelines for Safe Timing
The simplest rule is one hour per standard drink, counted from when you finish your last drink, plus at least one extra hour as a buffer. If you had five standard drinks and stopped at 11 p.m., waiting until at least 5 a.m. gives your body time to clear the alcohol, though 6 or 7 a.m. provides a better margin of safety.
For a heavier night out (eight or more drinks), the math pushes into late morning or early afternoon. Many people underestimate this because they feel “fine” after sleeping. Sleep doesn’t accelerate metabolism. Your liver processes alcohol at the same rate whether you’re awake or asleep.
If you’re a smaller person, a woman, or you drank on an empty stomach, add extra time. And if you’re under 21 or hold a commercial license, the margin for error is essentially zero, since even trace amounts can result in legal consequences.