Your body clears alcohol at a fixed rate of roughly one standard drink per hour, but traces of liquor can linger far longer depending on how you’re being tested. A blood or breath test can pick up alcohol for about 12 hours, a saliva test for up to 24 hours, a urine test for up to 72 hours, and a hair test for up to 90 days. The type of test matters just as much as how much you drank.
How Your Body Processes Alcohol
Your liver does nearly all the work of breaking down alcohol, and it operates at a remarkably steady pace. Once the enzymes responsible for processing alcohol become saturated (which happens quickly, even after one or two drinks), the rate locks in at about 0.015 to 0.020 BAC per hour. That translates to roughly one standard drink every 60 minutes, and nothing speeds it up. Not coffee, not water, not food, not a cold shower.
A standard drink in the United States contains about 14 grams of pure alcohol. That’s 1.5 ounces of 80-proof liquor, 5 ounces of wine, or 12 ounces of regular beer. Many cocktails contain more than one standard drink, which means a single mixed drink could take two or more hours to clear.
This fixed-rate processing has a practical consequence: if you reach a BAC of 0.08 (the legal limit in every state except Utah, where it’s 0.05), it takes roughly four to five hours for your blood alcohol to drop back to zero. Double that BAC, and you’re looking at eight to ten hours.
Detection Windows by Test Type
How long alcohol shows up depends entirely on what’s being tested. Here’s what each method can detect:
- Blood and breath: Alcohol is detectable for up to about 12 hours after your last drink. These tests measure active alcohol circulating in your system.
- Saliva: An oral fluid test can pick up alcohol for up to 24 hours.
- Urine (standard): A basic urine test detects alcohol for roughly 12 to 24 hours.
- Urine (EtG): This more sensitive test looks for a metabolic byproduct your body produces when it breaks down alcohol. After a few drinks, EtG can show up in urine for 48 hours, and sometimes 72 hours or longer after heavier drinking.
- Hair: A hair strand test can reveal alcohol use from 1 to 6 months prior, though most results cover a 3-to-6-month window since people regularly cut or trim their hair.
If you’re facing a workplace or court-ordered test, the EtG urine test is common because of its long detection window. It’s sensitive enough to flag drinking that happened days earlier, even when all other signs of alcohol have left your body.
Why Some People Process Liquor Slower
The one-drink-per-hour rule is an average. Several biological factors shift the timeline in either direction.
Body composition plays a significant role. Men generally carry more body water and less body fat than women of similar weight, which gives alcohol a larger volume to distribute into. The result: women typically reach a higher BAC than men after consuming the same amount, and it takes longer to clear. Body size matters too. A 120-pound person will feel and retain a drink much longer than a 200-pound person, simply because there’s less tissue to absorb the alcohol.
Age slows things down. Liver function declines gradually over time, and older adults process alcohol less efficiently. Whether you’ve eaten recently also matters. Food in your stomach slows absorption, which means your BAC peaks lower and comes down faster than it would on an empty stomach. Chronic heavy drinking can eventually damage the liver to the point where metabolism slows further, though in some long-term drinkers the liver temporarily ramps up enzyme production, creating a misleading sense of tolerance.
Hangovers Don’t Mean You’re Still Impaired
Hangover symptoms typically begin when your blood alcohol drops to or near zero. That means the headache, nausea, and fatigue you feel the morning after aren’t caused by alcohol still circulating in your blood. They’re the aftereffects of dehydration, inflammation, and disrupted sleep. You may feel terrible, but a breathalyzer would likely read clean.
There’s a narrow exception. If you drank heavily enough that your BAC was very high at bedtime, you could still have measurable alcohol in your system the next morning. Someone who stops drinking at midnight with a BAC of 0.20 wouldn’t reach zero until roughly 10 a.m. or later. In that scenario, hangover symptoms and actual impairment overlap, and driving would still be both dangerous and illegal.
How Many Drinks, How Many Hours
Because metabolism is so predictable, you can estimate clearance time with simple math. Take the number of standard drinks you consumed and subtract one for each hour since you stopped drinking. If the result is greater than zero, alcohol is likely still in your blood.
Some rough benchmarks for a person of average weight:
- 2 standard drinks: about 2 to 3 hours to reach zero BAC
- 4 standard drinks: about 4 to 5 hours
- 6 standard drinks: about 6 to 8 hours
- 10 standard drinks: about 10 to 13 hours
These estimates assume you stopped drinking at a defined point. If you’re sipping over several hours, your body is metabolizing some alcohol while you’re still adding more, which complicates the math. The safest approach after a night of heavy drinking is to wait longer than you think you need to, especially before driving. Many morning-after DUI arrests happen to people who genuinely believed they were sober.
Keep in mind that liquor often hits harder than beer or wine simply because it’s easy to pour more than a standard serving. A generous pour of whiskey or a strong cocktail can contain two or three standard drinks in a single glass, which means your liver needs two or three hours just to clear that one round.