The short answer: alcohol itself is usually gone from your blood within 12 to 24 hours, because the liver burns it off at a nearly fixed rate of about 0.015% BAC per hour. But the metabolites your body produces along the way stick around far longer, and some tests find them for days or even months. Here's the elimination math, the detection window for every major test type, and the morning-after arithmetic people get wrong.
Almost all of it, over 90%, is metabolized by the liver. The rest leaves through breath, urine, and sweat, which is why breathalyzers can estimate blood alcohol at all. The liver does this work at a rate that's essentially fixed: roughly one standard drink per hour, which translates to about 0.015 percentage points of BAC per hour for the average person. Individual rates fall in a range of about 0.010% to 0.020% per hour depending on liver health, genetics, and how regularly someone drinks.
That fixed rate is the whole game. Drinking faster than your liver clears means BAC climbs; stopping means it falls in a straight line. A standard US drink is 14 grams of pure alcohol: a 12-oz beer at 5% ABV, a 5-oz glass of wine at 12%, or a 1.5-oz shot of 80-proof spirits. Two of those in an hour is already more than most livers can process.
Divide your peak BAC by 0.015 and you have your answer in hours. The table below runs that math for common peaks:
| Peak BAC | Hours to 0.00% | Typical scenario (Widmark estimate) |
|---|---|---|
| 0.05% | ~3.5 hours | Two drinks, small adult, one hour |
| 0.08% | ~5.5 hours | Legal per-se limit reached, 49 states |
| 0.10% | ~6.5–7 hours | Four drinks in two hours, average adult |
| 0.12% | ~8 hours | Five to six drinks across an evening |
| 0.15% | ~10 hours | Heavy night; enhanced-penalty threshold in most states |
| 0.20% | ~13.5 hours | Very heavy drinking; blackout territory |
The catch: you can't feel where you are on this table. Perceived sobriety returns well before BAC does. For an estimate of where you'd land after a specific number of drinks, the BAC calculator runs the Widmark formula with your weight, sex, drink count, and hours elapsed.
It depends on weight, sex, and time, more than most people expect. Using the Widmark equation, here's roughly how many standard drinks it takes to hit 0.08% within the first hour of drinking:
| Body weight | Men (r = 0.73) | Women (r = 0.66) |
|---|---|---|
| 120 lbs | 2.7 drinks | 2.4 drinks |
| 140 lbs | 3.1 drinks | 2.8 drinks |
| 160 lbs | 3.6 drinks | 3.3 drinks |
| 180 lbs | 4.0 drinks | 3.7 drinks |
| 200 lbs | 4.5 drinks | 4.1 drinks |
Women reach higher BACs at the same weight because alcohol distributes in body water, and the distribution ratio differs by sex. These are estimates, not promises — food, drink pacing, and body composition all move the real number. And remember the limits below 0.08: Utah set its per-se limit at 0.05% (the strictest in the US), commercial drivers are held to 0.04%, and drivers under 21 face zero-tolerance limits of 0.01% to 0.02% in every state.
There are two different things a test can look for: alcohol itself, or the metabolites left after your body processes it. That distinction is why detection windows vary so wildly between test types:
| Test type | What it measures | Typical detection window |
|---|---|---|
| Breath | Current blood alcohol | 12–24 hours |
| Blood (alcohol) | Current blood alcohol | Up to ~12 hours |
| Saliva | Current/recent alcohol | 12–24 hours |
| Urine (traditional) | Recent alcohol | 12–24 hours, up to 48 |
| Urine (EtG) | Alcohol metabolite | 24–72 hours, up to 80 after heavy use |
| Blood (PEth) | Alcohol biomarker | Roughly 2–3 weeks |
| Hair | Long-term biomarkers | Up to ~90 days |
EtG stands for ethyl glucuronide, a direct metabolite that appears within about an hour of drinking. It's the test used in courts and monitoring programs precisely because it sees yesterday's drinking that a breath test misses. Windows shift with how much was consumed and how fast it was cleared, so treat these as commonly cited ranges rather than guarantees — heavy drinking pushes every window toward its upper end.
Yes, and it's one of the most common ways people get a DUI. Say you leave a party at midnight with a BAC around 0.15%. Your liver clears about 0.015% per hour, so by 6 a.m. you're near 0.06% — under 0.08, but still measurably impaired, illegal in Utah, and over the 0.04% commercial limit. Full zero arrives around 10 a.m. Sleep doesn't metabolize alcohol; only elapsed time does, and a few hours of it counts for less than people hope.
It works in reverse too. Coffee makes you feel alert without lowering BAC, and a big breakfast doesn't either. The reliable rule is hours since the last drink, not how you feel at the wheel.
No. Not coffee, not cold showers, not exercise, not food after the fact. The liver's 0.015% per hour pace is close to unchangeable, which is why every myth about sobering up is really a myth about feeling sober. Food before or while drinking slows absorption and keeps the peak lower — that's real prevention. Water counters dehydration. But once the alcohol is in your blood, the only thing that removes it is the same fixed-rate clock, running no faster for anyone.
Enter weight, drinks, and hours elapsed — the calculator returns an estimated BAC, impairment status, and hours to zero.
BAC Calculator →Alcohol leaves your blood at about 0.015% BAC per hour, full stop, which makes the time-to-zero math something you can do on a napkin: a 0.12% night is an eight-hour clock. Tests, though, see much further back than your blood does — breath and blood to roughly a day, EtG urine to three or four days after heavy drinking, hair to three months. If you're planning an evening rather than explaining one, a wedding alcohol calculator sizes the buy for the guest list, and if the evening already went wrong, a car insurance rate increase calculator shows what a DUI does to premiums for years afterward.
No. Water helps with dehydration, which is why it helps a hangover, but it does nothing to your blood alcohol level. The liver clears alcohol at a nearly fixed rate of about 0.015% BAC per hour, and no drink, shower, or snack changes that clock.
A breathalyzer detects current blood alcohol, not past drinking, so it reads positive only while your BAC is above zero. For most people that means alcohol is gone from the breath within 12 to 24 hours of the last drink, sooner after light drinking.
Rarely, yes. EtG is sensitive enough that heavy exposure to alcohol-based hand sanitizer, some mouthwashes, fermented foods, or kombucha can produce low-level positives. Confirmatory testing and context are used in monitoring programs for exactly this reason.
Not automatically. If you closed the night at 0.15% around midnight, six hours of sleep leaves you near 0.06%, still impaired and over the limit in Utah and for commercial drivers. Only time clears alcohol, so count hours from your last drink, not from when you woke up.
Weight changes how high your BAC climbs, not how fast it falls. A 120-lb woman and a 200-lb man who drink the same amount reach very different peaks, but both burn off about 0.015% per hour once the alcohol is in the blood.