Alcohol is typically eliminated from your bloodstream at a rate of about 15 to 20 mg/dL per hour, which means most people clear roughly one standard drink every 60 to 90 minutes. A night of moderate drinking (three or four drinks) generally leaves your blood alcohol-free within 6 to 8 hours, while heavier drinking can take 12 hours or longer to fully clear.
That said, the actual timeline depends on how much you drank, your body composition, whether you ate beforehand, and your biological sex. Here’s how it all works.
How Your Body Processes Alcohol
More than 90% of the alcohol you drink is eventually broken down in your liver. Less than 10% leaves your body through breath, sweat, and urine. The liver handles alcohol in two steps: first, enzymes convert ethanol into a toxic intermediate compound called acetaldehyde. Then a second set of enzymes rapidly converts acetaldehyde into acetate, which your body breaks down into carbon dioxide, water, and fatty acids.
The key thing to understand is that your liver can only process alcohol at a fixed pace. No amount of coffee, water, or food will speed it up once alcohol is already in your blood. The average person eliminates alcohol at about 15 mg/dL per hour on an empty stomach and closer to 15 to 20 mg/dL per hour with food. People who drink heavily over time can metabolize faster, sometimes 25 to 35 mg/dL per hour, because chronic drinking ramps up a secondary enzyme system in the liver. But across the general population, the full range runs from about 10 to 35 mg/dL per hour.
What Counts as One Drink
A standard drink in the United States contains about 14 grams of pure alcohol. That’s the amount in a 12-ounce beer at 5% alcohol, a 5-ounce glass of wine at 12%, or a 1.5-ounce shot of liquor at 40%. Craft beers, large pours of wine, and cocktails with multiple shots often contain two or three standard drinks in a single glass, which is why people routinely underestimate how much they’ve actually consumed.
Realistic Timelines by Number of Drinks
Using the average clearance rate of about 15 to 20 mg/dL per hour, here are rough estimates for how long alcohol stays in your bloodstream after your last sip. These assume you’re an average-sized adult who drank at a moderate pace:
- 1 standard drink: about 1 to 2 hours
- 2 standard drinks: about 2 to 4 hours
- 4 standard drinks: about 5 to 8 hours
- 6 standard drinks: about 7 to 11 hours
- 8 standard drinks: about 10 to 15 hours
These are approximations. A smaller person, a woman, or someone who drank on an empty stomach will trend toward the longer end. A larger, muscular man who ate a full meal will trend shorter.
Why the Timeline Varies So Much
Several factors push your clearance time up or down significantly.
Biological sex. Women tend to reach higher blood alcohol levels than men even when drinking the same amount. Women generally have higher body fat percentages, lower body water, and fewer of the stomach enzymes that begin breaking down alcohol before it reaches the bloodstream. The result is more alcohol staying in circulation for longer.
Body composition. Muscle tissue absorbs alcohol; fat does not. Two people who weigh the same can have very different blood alcohol levels if one carries more muscle and the other more fat. This is also why body weight alone isn’t a reliable predictor.
Food. Eating before or while drinking slows absorption substantially. Food causes the valve at the bottom of your stomach to close during digestion, which keeps alcohol from reaching the small intestine, where most absorption happens. Greasy, high-protein, and fatty foods stay in the stomach longest and slow intoxication the most. This doesn’t change the elimination rate once alcohol is in your blood, but it does lower your peak blood alcohol level, which means less total time to clear.
Age. Older adults tend to reach higher blood alcohol concentrations than younger adults given the same dose. Research on elderly participants found their measured peak BAC was significantly higher than predicted, likely because body water decreases and body fat increases with age.
How Impairment Changes as BAC Drops
Your blood alcohol concentration (BAC) isn’t just a number for a breathalyzer. It maps to real, measurable changes in how your brain and body perform. Data from the National Highway Traffic Safety Administration breaks this down:
At a BAC of 0.02%, you’ll feel slightly relaxed with minor changes in mood and a subtle decline in your ability to track moving objects. At 0.05%, judgment is impaired, alertness drops, and you may have trouble with fine motor control like focusing your eyes. At 0.08%, the legal limit for driving in all 50 states, coordination is noticeably poor. Reaction time, balance, speech, and short-term memory are all affected. At 0.10%, reaction time and control are clearly deteriorated, with slurred speech and slowed thinking. By 0.15%, muscle control is severely reduced, balance is substantially impaired, and vomiting is common.
Above 0.15%, the risks escalate sharply. Blackouts, loss of consciousness, and life-threatening alcohol overdose become real possibilities. The threshold varies from person to person based on tolerance, age, medications, and how quickly the alcohol was consumed.
Blood Tests vs. Other Detection Methods
A standard blood test detects alcohol only while it’s actively circulating, which covers the timelines described above. But other testing methods have much longer detection windows.
Breath tests work similarly to blood, capturing alcohol over roughly the same short window. Urine tests can detect alcohol byproducts for 12 to 48 hours after your last drink, and some advanced urine tests that look for specific metabolites can extend that window to about 72 to 80 hours. Hair tests have the longest reach, detecting alcohol use patterns over 1 to 6 months, though they reflect repeated drinking rather than a single episode.
If you’re concerned about a specific test, what matters most is knowing which type it is. A blood or breath test only catches recent consumption, while urine and hair tests look further back.
Why BAC Calculators Aren’t Reliable
Online BAC calculators typically use the Widmark formula, which estimates blood alcohol based on the amount of alcohol consumed, your body weight, and a distribution factor that accounts for body water versus fat. The standard distribution factors used are 0.7 for men and 0.6 for women of normal weight, with adjustments for people who are heavier or leaner.
The problem is that this formula carries a margin of error of roughly 42%, with nearly half of that uncertainty coming from the distribution factor alone. In practical terms, two people of the same weight and sex can have meaningfully different BACs after identical drinks. These calculators give a ballpark, but they’re not precise enough to tell you whether you’re safe to drive or will pass a test at a specific time.