Most people lose between 0.015 and 0.020 BAC per hour. That rate is remarkably consistent: if you’re at the legal limit of 0.08, it takes roughly four to five hours to reach 0.00. Your liver does this work at a fixed pace, and almost nothing you do can speed it up.
The Standard Elimination Rate
Your body clears alcohol at about 0.015 to 0.020 BAC per hour. This isn’t an average that fluctuates with how drunk you are. Alcohol follows what pharmacologists call “zero-order kinetics,” meaning the rate stays constant regardless of how much alcohol is in your blood. Whether you’re at 0.05 or 0.20, your liver processes roughly the same amount each hour.
In practical terms, one standard drink (a 12-oz beer, 5-oz glass of wine, or 1.5-oz shot of liquor) raises most people’s BAC by about 0.02 to 0.03. So your liver needs roughly one to two hours to fully clear a single drink. Stack several drinks in a short window and you’re simply adding to a queue your liver works through at its own pace.
Why the Rate Varies Between People
While 0.015 to 0.020 is the standard range, individual rates can fall outside it. A study comparing different drinking populations found meaningful differences: people who rarely drink cleared alcohol at about 0.012 per hour on average, social drinkers at about 0.015, and people with alcohol dependence at about 0.030. Chronic heavy drinking causes the liver to recruit a secondary enzyme system that only activates after large amounts of alcohol, effectively doubling the clearance rate in some cases.
Biological sex matters too. Women generally absorb more alcohol and take longer to process it than men after drinking the same amount. This is largely because women tend to have a higher proportion of body fat and less body water, which concentrates alcohol in the bloodstream. Body size, weight, and overall body composition all shift the equation.
Genetics play a quieter but significant role. The two main liver enzymes that break down alcohol vary in efficiency from person to person based on inherited gene variants. Some populations carry enzyme variants that process alcohol faster but produce a toxic byproduct more quickly, leading to facial flushing and nausea. Others carry variants that slow the whole process down. You can’t know your exact rate without a controlled test, but the 0.015 to 0.020 range covers the large majority of adults.
How Your Liver Actually Processes Alcohol
Your liver handles about 90 to 95 percent of alcohol elimination. The process works in two steps. First, an enzyme converts alcohol into a toxic compound called acetaldehyde, which is a known carcinogen. This is the substance responsible for much of the damage heavy drinking causes. Second, another enzyme quickly converts acetaldehyde into acetate, a harmless compound your body breaks down into water and carbon dioxide.
The reason your liver can’t go faster is simple: these enzymes become fully saturated even at moderate blood alcohol levels. Think of it like a single-lane toll booth. No matter how many cars are lined up, only one can pass through at a time. Adding more alcohol doesn’t make the enzymes work harder. It just lengthens the line.
Nothing Speeds It Up
Coffee, cold showers, exercise, food, and water do not increase your BAC elimination rate. Research has specifically tested caffeine and energy drinks: adding them to alcohol did not change breath alcohol concentration at all, nor did caffeine improve alcohol-impaired driving performance. Coffee might make you feel more alert, but your BAC stays exactly where your liver’s pace dictates.
The only thing that lowers your BAC is time. Eating before or during drinking can slow absorption, meaning your BAC may not climb as high in the first place. But once alcohol is in your bloodstream, you’re waiting on your liver.
Estimating Your Timeline to 0.00
A simple way to estimate when you’ll be sober: take your current or estimated peak BAC and divide it by 0.015. That gives you a rough number of hours.
- BAC of 0.04: about 2.5 to 3 hours
- BAC of 0.08: about 4 to 5.5 hours
- BAC of 0.12: about 6 to 8 hours
- BAC of 0.16: about 8 to 11 hours
- BAC of 0.20: about 10 to 13 hours
These timelines start from your peak BAC, not from when you stopped drinking. Your BAC can continue rising for 30 to 60 minutes after your last drink, especially if you had food in your stomach slowing absorption. So the clock doesn’t start the moment you put your glass down.
Forensic scientists use a more precise version of this calculation called the Widmark equation, which factors in your body weight, sex, the total grams of alcohol consumed, and your personal elimination rate. It’s the standard tool in legal and medical settings, but for everyday purposes, dividing your estimated BAC by 0.015 gives you a reasonable ballpark.
Breathalyzers and Blood Tests
If you’re wondering how long alcohol stays detectable, the answer depends on the test. Breath and blood tests both measure current BAC, so they track your elimination rate in real time. Once you hit 0.00, standard breathalyzers and blood tests won’t detect anything.
One thing worth knowing: roadside breathalyzers tend to read about 15 percent lower than actual blood alcohol levels, based on a large study of nearly 1,900 traffic stops. The devices use an assumed ratio to convert breath alcohol to blood alcohol, and that ratio isn’t perfectly constant. It shifts depending on how recently you drank and whether your BAC is still rising or falling. A breath test shortly after your last drink may underestimate your true BAC.
Urine tests can detect alcohol metabolites for 12 to 24 hours after your last drink, and specialized urine panels can find certain byproducts for up to 72 to 80 hours. Hair tests extend the window to roughly 90 days, though these are rarely used outside of workplace or legal screening.