Your body eliminates alcohol at a nearly fixed rate of about one standard drink per hour. That works out to a blood alcohol concentration (BAC) drop of roughly 0.015 per hour, regardless of how much you’ve consumed. So if you stop drinking at a BAC of 0.08 (the legal limit in most U.S. states), it takes about five and a half hours to reach 0.00.
Why the Rate Is So Consistent
Most substances clear your system faster when there’s more of them present, because the enzymes responsible simply work harder. Alcohol is different. The primary enzyme that breaks it down in your liver gets overwhelmed almost immediately, even at low amounts of alcohol. Once that enzyme is maxed out, it can only process a fixed quantity per hour no matter how much is waiting in line. This is why drinking more doesn’t make your body work faster to catch up. It just extends the total time needed.
Your liver handles about 90% of alcohol processing. The remaining fraction leaves through your breath, sweat, and urine, which is why a breathalyzer works but also why you can’t sweat or urinate your way sober any faster. The liver converts alcohol into a toxic intermediate compound, which is then quickly broken down into a harmless substance your cells can use for energy. That middle step, where the toxic byproduct briefly exists, is partly responsible for hangovers and the nausea heavy drinkers experience.
What Counts as “One Drink”
In the U.S., a standard drink contains about 14 grams of pure alcohol. That’s 12 ounces of regular beer (5% alcohol), 5 ounces of wine (12%), or 1.5 ounces of distilled spirits (40%). The U.K. uses a smaller standard of 8 grams. This matters because your personal “drink count” might be off. A strong craft IPA at 8% in a pint glass is closer to two standard drinks, and a generous pour of wine at a restaurant often exceeds one. If you undercount your drinks, your estimate for how long alcohol stays in your system will be too low.
Factors That Speed Up or Slow Down Clearance
The one-drink-per-hour rule is an average, and several factors shift it in either direction.
Body composition: People with more body fat and less lean tissue end up with higher alcohol concentrations from the same number of drinks, because alcohol distributes mainly through water-rich tissue. A higher concentration doesn’t make the liver work faster, so it takes longer to clear.
Sex: Women generally have a higher proportion of body fat and lower levels of the enzyme that breaks down alcohol, which means BAC rises faster and falls more slowly compared to men of the same weight drinking the same amount.
Food: Eating a full meal before or while drinking makes a significant difference, though not in the way most people assume. Food primarily slows absorption, which lowers your peak BAC. In one study, people who drank on a full stomach only absorbed about 66 to 71% of the alcohol that fasting subjects did, and their peak BAC was roughly a third lower. The actual elimination rate from the liver stays about the same whether you’ve eaten or not, but because your peak is lower, you reach zero faster in real-world terms.
Liver health and genetics: Chronic heavy drinking can alter enzyme production over time, and certain genetic variations (particularly common in East Asian populations) affect how efficiently the liver processes alcohol’s toxic byproduct. Some medications also compete for the same liver pathways, slowing clearance.
How Long Alcohol Shows Up on Tests
Your BAC might hit zero hours before certain tests can still detect that you drank. Different testing methods have very different detection windows:
- Blood test: Detects alcohol for up to 12 hours after your last drink.
- Breathalyzer: Can pick up alcohol on your breath for 12 to 24 hours, depending on how much you consumed.
- Standard urine test: Alcohol itself clears urine relatively quickly, but a specialized urine test that looks for a metabolic byproduct (EtG) can detect drinking for 48 hours after a few drinks, and up to 72 hours or longer after heavier consumption.
- Hair follicle test: Can detect alcohol use for up to 90 days.
If you’re concerned about a specific test, the type of test matters far more than how much water you drink or whether you exercise beforehand. Neither hydration nor physical activity meaningfully speeds up liver metabolism.
Putting the Math Together
A practical way to estimate your timeline: count your standard drinks honestly, note the time you stopped drinking, and add roughly one hour per drink from that point. Four standard drinks finished at midnight means your body likely needs until about 4 a.m. to fully process the alcohol. If your BAC was particularly high, say after six or seven drinks, you could still be above the legal driving limit well into the next morning.
Keep in mind that “feeling sober” and “being at zero BAC” are not the same thing. Your brain adjusts to alcohol’s effects over the course of a drinking session, so you may feel relatively normal while your BAC is still elevated. The only thing that reliably removes alcohol from your system is time. Coffee, cold showers, and fresh air may make you feel more alert, but they do nothing to change the rate your liver is working.