Alcohol leaves your bloodstream at a fairly consistent rate of about 0.015 BAC per hour. That means if you’re at the legal driving limit of 0.08, it will take roughly 5 hours for your blood alcohol to drop to zero. A heavier night of drinking that pushes your BAC to 0.15 could take 10 hours to fully clear.
That rate is largely fixed. Unlike many substances your body processes, alcohol elimination doesn’t speed up significantly no matter what you do. Understanding why helps explain the timeline and what actually affects it.
What 0.015 Per Hour Looks Like
Your liver does nearly all the work of breaking down alcohol, and it operates at a near-constant speed. The primary enzyme responsible, alcohol dehydrogenase, converts ethanol into a toxic intermediate compound called acetaldehyde, which is then quickly converted into acetate and eventually into water and carbon dioxide that your body can easily get rid of. This process runs at a rate that lowers your BAC by about 0.015 per hour, with some individual variation between 0.015 and 0.020.
A second enzyme system kicks in when you’ve had large amounts of alcohol, adding some extra processing capacity. But for most drinking scenarios, the standard rate holds. Here’s what that means in practice for different BAC levels:
- BAC 0.04 (one to two drinks for most people): roughly 2.5 to 3 hours to reach zero
- BAC 0.08 (the legal limit): about 4 to 5.5 hours
- BAC 0.15 (heavy drinking): about 10 hours
- BAC 0.20 (very heavy drinking): about 13 hours
These are estimates for complete elimination. You’ll feel functional well before your BAC hits zero, but alcohol is still measurably present and still affecting your brain, reaction time, and judgment during that entire window.
Why Your Timeline May Differ
The 0.015 rate is an average, and several factors determine where you fall on the spectrum. Body size matters most directly: a larger person has more blood volume, so the same number of drinks produces a lower peak BAC, which means less total time to clear. Body composition plays a role too. Muscle tissue contains more water than fat tissue, and alcohol dissolves in water. Someone with more muscle and less body fat will distribute alcohol more efficiently, resulting in a lower BAC from the same amount of alcohol.
This is one reason women generally reach higher blood alcohol levels than men after the same number of drinks. Women on average have smaller body sizes, more body fat relative to muscle, and less total body water. The CDC notes that women absorb more alcohol and take longer to process it compared to men. Hormonal differences also play a role in how quickly the liver works through the alcohol load.
Food in your stomach slows absorption but doesn’t change the elimination rate once alcohol is in your bloodstream. Drinking on an empty stomach means a faster, higher peak BAC, which then takes longer to clear. Eating before or while drinking won’t help your liver work faster, but it does keep the peak lower in the first place.
What Counts as One Drink
Most people underestimate how much they’ve actually consumed, which throws off any timeline calculation. A standard drink in the United States contains 0.6 ounces (14 grams) of pure alcohol. That’s equivalent to:
- Beer: 12 ounces at 5% alcohol
- Wine: 5 ounces at 12% alcohol
- Liquor: 1.5 ounces (one shot) of 80-proof spirits
- Malt liquor: 8 ounces at 7% alcohol
A craft IPA at 8% in a 16-ounce pint glass is closer to two and a half standard drinks. A generous pour of wine at a dinner party could easily be two. If you’re estimating your clearance time based on “three drinks,” make sure you’re counting accurately.
Nothing Speeds Up the Process
Coffee, cold showers, exercise, food, and water do not accelerate alcohol metabolism. Coffee can make you feel more alert, which is arguably more dangerous since it masks how impaired you actually are. Water and food are good for preventing a hangover, but they won’t change when your BAC reaches zero. Your liver processes alcohol at its own pace, and there is no reliable way to increase that pace.
This is why the only guaranteed strategy for being sober enough to drive, work, or do anything requiring clear judgment is time. If you stopped drinking at midnight and your BAC peaked at 0.15, you may still have alcohol in your blood at 10 a.m. the next morning.
How Long Alcohol Shows Up on Tests
Even after your BAC hits zero and alcohol is functionally gone from your blood, certain tests can detect that you were drinking. The detection windows vary significantly depending on the type of test:
A breathalyzer typically detects alcohol for 4 to 6 hours after your last drink, though it can sometimes register positive up to 24 hours later. Standard blood alcohol tests work within a similar 12-hour window. These tests measure ethanol itself, so once your liver has processed it all, you’ll test clean.
Urine tests have a wider range. A basic ethanol urine test detects alcohol for about 12 hours. But tests that look for alcohol byproducts (metabolites your body produces while breaking down ethanol) can detect drinking for 24 to 72 hours, though they’re considered most reliable within the first 24 hours. There are also specialized blood tests that detect a compound your body creates when alcohol interacts with cell membranes, and these can flag drinking from one to three weeks prior.
For most practical purposes, the question people actually care about is when they’ll be under 0.08 or at zero. The answer comes down to simple math: take your estimated peak BAC, divide by 0.015, and that’s roughly how many hours you need. If you’re not sure of your peak BAC, err on the side of more time. The liver doesn’t negotiate.