Your body clears alcohol at a fairly fixed rate: most people lower their blood alcohol concentration (BAC) by about 0.015 per hour. That means if you reach the legal limit of 0.08, it takes roughly 4 to 5 hours to get back to zero. Heavier drinking pushes that timeline much further out, sometimes past 24 hours.
The Basic Rate of Elimination
Your liver does the vast majority of the work. It converts alcohol into a toxic intermediate compound, then quickly breaks that down into acetate, which the rest of your body converts to water and carbon dioxide. This process runs at a near-constant speed regardless of what you do after drinking. Coffee, cold showers, and exercise don’t accelerate it.
The central estimate is a BAC drop of 0.015 per hour, though individual rates range from about 0.01 to 0.02 per hour. That narrow range means you can estimate your timeline with reasonable accuracy once you know your peak BAC. At the low end of the range, someone at 0.08 would need about 8 hours to clear completely. At the high end, closer to 4 hours. Most people fall in the middle.
How Many Drinks Changes the Math
A single standard drink (one beer, one glass of wine, one shot) raises BAC modestly, and for most people it clears within 1 to 2 hours. The problem is that drinks stack. Your liver can only process a fixed amount per hour, so every additional drink adds to the queue.
The numbers get serious with heavier drinking. Data from the University of Arizona illustrates this clearly: a 140-pound man who has 9 drinks needs roughly 15 hours to reach a BAC of zero. A 100-pound woman who has 9 drinks needs about 26 hours. That means someone who finishes heavy drinking at midnight could still have measurable alcohol in their blood well into the next afternoon or evening.
This is why “sleeping it off” is unreliable. Eight hours of sleep after a night of heavy drinking often isn’t enough to fully clear the alcohol. You can wake up still legally impaired and not realize it.
What Affects Your Personal Timeline
Several factors influence how quickly you reach peak BAC and how fast you come back down.
- Body weight and composition. Larger bodies distribute alcohol across more tissue, resulting in a lower peak BAC from the same number of drinks. This is one reason the same amount of alcohol hits a smaller person harder and takes longer to clear.
- Sex. Women generally reach higher BAC levels than men of similar weight from the same amount of alcohol, partly due to differences in body water content and enzyme activity.
- Food in your stomach. Eating before or while drinking slows alcohol absorption significantly. Solid meals delay it more than liquid ones, because food slows the rate at which your stomach empties into the small intestine. Some research also suggests food slightly increases the rate of elimination, giving you a double benefit: a lower peak BAC and marginally faster clearance.
- Drinking history. Long-term heavy drinking changes liver enzyme activity. Chronic drinkers often produce more of certain processing enzymes, which can speed up alcohol metabolism. But this comes with serious trade-offs, including liver damage and disrupted metabolism of medications and other substances.
Detection Windows by Test Type
If you’re wondering about a specific test, the answer depends entirely on what’s being measured. Standard blood and breath tests detect alcohol itself, while certain urine and hair tests detect byproducts your body creates during processing.
- Blood test: up to 12 hours
- Breathalyzer: 12 to 24 hours
- Standard urine test: 12 to 24 hours (up to 72 hours or more after heavy drinking)
- Saliva test: up to 12 hours
- Hair follicle test: up to 90 days
EtG Urine Tests
EtG tests deserve special attention because they’re commonly used in probation, workplace, and treatment monitoring. These tests don’t look for alcohol directly. They detect a metabolic byproduct that lingers much longer.
The commonly cited window is “up to 80 hours,” but the practical reality is more nuanced. Commercially available EtG tests are typically only reliable for about 24 hours. After heavy drinking, detection can extend to 72 or even 80 hours, but sensitivity drops sharply over time. A high positive result (above 1,000 ng/mL) generally indicates same-day drinking or heavy drinking the day before. A low positive (500 to 1,000 ng/mL) could mean drinking one or two days prior, or light drinking within 24 hours. Very low positives (100 to 500 ng/mL) are the hardest to interpret and could reflect heavy drinking a few days earlier, recent light drinking, or even exposure to alcohol-based hand sanitizers, mouthwash, or certain cosmetics.
False positives are a real concern with EtG tests. Fermented foods, non-alcoholic beverages, and alcohol-based hygiene products can all trigger them.
BAC of Zero vs. Feeling Normal
Reaching a BAC of 0.00 doesn’t mean you’re back to baseline. Hangover symptoms, including headache, nausea, fatigue, and impaired concentration, typically peak after your BAC has already dropped to zero. The inflammation, dehydration, and disrupted sleep caused by alcohol linger independently of blood alcohol levels.
This means there’s a gap between “no longer legally impaired” and “actually functioning well.” After a heavy night, you may blow 0.00 on a breathalyzer and still have slower reaction times and worse judgment than usual. For anything requiring sharp focus, like driving long distances or operating equipment, factor in recovery time beyond just the hours needed to clear the alcohol itself.
Practical Estimates by Drinking Level
These are approximate times to reach a BAC of zero for an average-sized adult, starting from when you stop drinking:
- 1 to 2 standard drinks: 1 to 3 hours
- 3 to 4 standard drinks: 3 to 6 hours
- 5 to 6 standard drinks: 6 to 10 hours
- 7 to 9 standard drinks: 10 to 18 hours (longer for smaller individuals)
Remember that a “standard drink” is 12 ounces of regular beer, 5 ounces of wine, or 1.5 ounces of liquor. Many cocktails and craft beers contain significantly more alcohol than one standard drink, so count carefully. A strong IPA in a pint glass could count as nearly two drinks, and a generous pour of wine at home often exceeds the standard 5-ounce measure.
If you’re under 21, the legal threshold is even more demanding. Most states make it illegal to drive with any detectable amount of alcohol in your system, which means you’d need to be completely at zero, not just below 0.08.