Your body eliminates alcohol at a fixed rate of about one standard drink per hour, but traces can linger far longer depending on the type of test. A 1.5-ounce shot of liquor (40% ABV) contains the same 14 grams of pure alcohol as a 12-ounce beer or a 5-ounce glass of wine, so the type of drink matters less than how much total alcohol you consumed.
How Your Body Processes Alcohol
Almost all the alcohol you drink is broken down in your liver. An enzyme converts ethanol into a toxic intermediate compound, which a second enzyme then converts into a harmless substance that your body breaks down further into water and carbon dioxide. The process is straightforward, but there’s a bottleneck: the liver can only produce so much of these enzymes at a time.
This creates what chemists call a fixed-rate reaction. Unlike most substances, where your body clears them faster when there’s more in your bloodstream, alcohol disappears at the same steady pace no matter how much you drank. Drinking more doesn’t speed up the process. It just means the line is longer. Your blood alcohol concentration (BAC) drops at a rate of roughly 0.015 to 0.020 per hour. Someone who reaches a BAC of 0.10 (above the legal driving limit in every U.S. state) would need 5 to 10 hours to return to 0.00.
Factors That Change Your Timeline
The “one drink per hour” rule is an average, and several biological factors push your personal rate higher or lower.
- Biological sex: Women produce about 40% less of the primary alcohol-processing enzyme in their livers than men do. This means women typically clear alcohol more slowly and reach higher BAC levels from the same number of drinks.
- Body size: A larger body has more blood volume and more water to dilute the alcohol, so the same drink produces a lower peak BAC in a heavier person.
- Food intake: Drinking on an empty stomach allows alcohol to absorb faster, creating a higher and quicker peak. Food in your stomach slows absorption but doesn’t change how fast your liver works once the alcohol is in your blood.
- Liver health: Chronic heavy drinking, liver disease, and certain medications can all reduce the liver’s processing capacity.
- Genetics: Enzyme production varies between individuals and across ethnic populations, which is why some people flush or feel ill after small amounts of alcohol.
Detection Windows by Test Type
How long alcohol shows up depends entirely on what’s being tested. The alcohol itself leaves your blood relatively quickly, but your body produces byproducts that stick around much longer.
Blood and Breath
A blood test can detect alcohol for up to 12 hours after your last drink. Breathalyzers work on a similar timeline, typically detecting alcohol for 12 to 24 hours depending on how much you consumed. These tests measure active alcohol in your system, so once your liver finishes processing, you’ll test clean.
Urine
A standard urine test picks up alcohol for roughly 12 to 24 hours. But many workplaces, courts, and treatment programs now use a more sensitive urine test that detects a specific metabolite your body creates when processing alcohol (often called an EtG test). After a few drinks, this metabolite can appear in urine for up to 48 hours. After heavier drinking, it may be detectable for 72 hours or longer.
Hair
Hair follicle tests have the longest detection window. Alcohol metabolites get incorporated into the hair shaft as it grows, creating a record of consumption that typically covers 1 to 6 months. Most testing labs analyze the most recent 3 to 6 months of growth, though longer hair could theoretically reveal older use.
How Many Drinks Equals How Many Hours
Since your liver clears alcohol at a nearly constant rate, you can estimate your timeline with simple math. Each standard drink raises your BAC by roughly 0.02 to 0.03, depending on your body size and sex. Your BAC then drops by about 0.015 to 0.020 per hour.
If you have three shots of liquor over an hour and reach a BAC around 0.07, expect roughly 4 to 5 hours before you’re back to zero. Six drinks pushing your BAC to 0.12 or higher could take 7 to 10 hours. These numbers explain why people who drink heavily in the evening can still be over the legal limit the next morning.
Nothing speeds this process up. Coffee, cold showers, exercise, and food may make you feel more alert, but they don’t change how fast your liver works. The only thing that actually lowers your BAC is time.
Liquor vs. Beer vs. Wine
A standard serving of liquor, beer, or wine all contain the same 14 grams of pure alcohol. Your body doesn’t process spirits any differently than it processes beer. What makes liquor riskier in practice is how easy it is to pour more than a standard serving. A “double” at a bar is two standard drinks. A generous home pour of whiskey can easily be two or three. If you’re trying to estimate how long alcohol will be in your system, count your actual ounces rather than your number of “drinks.”