Your body eliminates alcohol at a roughly fixed rate of about 0.015 to 0.017 percent blood alcohol concentration (BAC) per hour. For most people, that works out to processing about one standard drink every 60 to 90 minutes. Unlike many other substances, alcohol breaks down on a near-constant schedule that you can’t meaningfully speed up with coffee, cold showers, or any other trick.
What One Drink Actually Means
In the United States, a standard drink contains 0.6 ounces (14 grams) of pure alcohol. That’s one 12-ounce beer at 5% alcohol, one 5-ounce glass of wine at 12%, or one 1.5-ounce shot of liquor at 40%. People routinely underestimate how many standard drinks they’ve had because restaurant pours, craft beers, and cocktails often contain significantly more alcohol than these benchmarks. A strong IPA in a pint glass can easily count as two standard drinks.
This matters because your liver processes alcohol at a nearly fixed pace regardless of how much you’ve consumed. If you drink faster than your body can metabolize, the excess stays in your bloodstream and your BAC climbs. Three drinks in an hour means roughly two drinks’ worth of alcohol is still circulating while your liver works through the queue one drink at a time.
How Your Liver Breaks Down Alcohol
About 90 to 95 percent of the alcohol you drink is processed in the liver. The rest leaves through your breath, sweat, and urine. The main breakdown pathway uses two enzymes working in sequence. The first, alcohol dehydrogenase (ADH), converts ethanol into acetaldehyde, a toxic compound and known carcinogen. The second enzyme, aldehyde dehydrogenase (ALDH), quickly converts that acetaldehyde into acetate, a relatively harmless substance your body then breaks down into water and carbon dioxide.
The reason acetaldehyde matters: it’s responsible for many of the unpleasant effects of drinking, including nausea and flushing. In most people, the second enzyme works fast enough that acetaldehyde doesn’t linger. But in people with certain genetic variants, it builds up, which explains why some individuals feel sick after even small amounts of alcohol.
There’s also a backup system called the microsomal ethanol-oxidizing system (MEOS), which uses a different enzyme called CYP2E1. At low blood alcohol levels, this pathway handles only a small fraction of the work. But it becomes more important at higher alcohol concentrations because the primary ADH enzyme is already working at full capacity. In people who drink heavily over time, CYP2E1 activity increases 4 to 10 fold, which partially explains why heavy drinkers develop metabolic tolerance and can process alcohol somewhat faster than occasional drinkers.
Why the Rate Varies From Person to Person
The 0.015 BAC-per-hour figure is an average. Several factors push your personal rate higher or lower.
Body size and composition. BAC is a function of how much alcohol is dissolved in your body’s water. Larger people have more total body water, so the same number of drinks produces a lower BAC. This is also why two people of the same weight but different body compositions can have different BAC levels after identical drinks.
Biological sex. Women generally reach higher BAC levels than men after the same amount of alcohol, even when body weight is equal. One major reason: men have highly active forms of ADH in their stomachs, which can break down up to 30% of alcohol before it ever reaches the bloodstream. Women produce almost no ADH in the stomach, meaning more alcohol passes intact into the bloodstream. On top of that, the ADH in the female liver tends to be less active than its counterpart in males. Women also typically carry a higher proportion of body fat and less water than men of the same weight, concentrating alcohol in a smaller fluid volume.
Genetics. Variations in the genes coding for ADH and ALDH enzymes have an outsized effect. Certain ADH gene variants, common in East Asian populations, produce an enzyme with roughly 40 times more activity than the standard version. This means alcohol converts to toxic acetaldehyde extremely fast. If the person also carries a less active version of the ALDH gene, that acetaldehyde accumulates, causing intense facial flushing, nausea, and rapid heartbeat. This combination is a strong deterrent to heavy drinking and is associated with lower rates of alcohol use disorder in these populations.
Food in your stomach. Eating before or while drinking slows the rate at which alcohol enters your small intestine, where most absorption happens. Food doesn’t change how fast your liver works, but it lowers your peak BAC by spreading absorption over a longer window. This gives your liver more time to keep up with incoming alcohol rather than falling behind. Research shows that food increases the proportion of alcohol broken down before it reaches general circulation, with first-pass metabolism jumping from about 4% on an empty stomach to around 30% when food is present.
What Doesn’t Speed Up Metabolism
Coffee, energy drinks, cold showers, exercise, and fresh air do not increase the rate at which your liver processes alcohol. Caffeine can make you feel more alert, which creates the dangerous illusion of sobriety while your BAC remains unchanged. Your liver enzymes work at a genetically determined pace, and no external stimulus makes them faster. Time is the only thing that actually lowers your BAC.
Heavy drinkers do develop some metabolic tolerance through the induction of CYP2E1, the backup enzyme pathway. But this isn’t a benefit. The same enzyme that helps process extra alcohol also converts many common medications and environmental chemicals into more toxic forms, making heavy drinkers more vulnerable to liver damage from substances that would be harmless at normal exposure levels. This increased enzyme activity persists for days to weeks after someone stops drinking.
How Long Alcohol Stays Detectable
Even after you feel sober, alcohol or its byproducts may still be measurable depending on the type of test.
- Blood and breath: Alcohol is typically detectable as long as your BAC is above zero. For someone who reaches a BAC of 0.08 (the legal limit for driving in most U.S. states), it takes roughly 5 to 6 hours for the liver to clear all the alcohol.
- Urine (standard test): Alcohol itself clears from urine within a few hours after your last drink, roughly tracking your BAC timeline.
- Urine (EtG test): A more sensitive test that detects a metabolic byproduct called ethyl glucuronide. After a few drinks, EtG can show up in urine for up to 48 hours. After heavier drinking, detection can extend to 72 hours or longer.
Practical Math for Estimating Your Timeline
A rough formula, originally developed by Swedish chemist Erik Widmark in the 1930s and still used today, estimates BAC based on the amount of alcohol consumed and a person’s body weight. The core relationship is straightforward: BAC rises proportionally with the amount of alcohol you drink and falls inversely with your body weight.
For a simple estimate, count your standard drinks, figure that each one raises your BAC by roughly 0.02 to 0.03 (depending on your size and sex), then subtract 0.015 for each hour that has passed since you started drinking. This is a rough guide, not a precise measurement. Individual variation in enzyme activity, stomach contents, and genetics can shift the real number meaningfully in either direction. The only reliable way to know your BAC is to measure it directly with a calibrated breathalyzer or blood test.
If you’ve had four standard drinks over two hours and you’re an average-sized man, your BAC might be in the range of 0.06 to 0.08. From that point, clearing to zero would take another 4 to 5 hours. For a smaller woman with the same intake, peak BAC would typically be higher and the wait correspondingly longer.