How Long Does Alcohol Stay in Your System?
Short answer: your liver clears about one standard drink per hour, so alcohol leaves your blood within hours, but tests can detect it far longer: up to 24 hours on your breath, up to 72+ hours in urine, and up to 90 days in hair. Start with your estimated BAC to see where you are right now.
Detection windows by test type
| Test | Detection window | Notes |
|---|---|---|
| Blood | Up to ~12 hours | Tracks actual BAC; drops ~0.015% per hour |
| Breath | 12 to 24 hours | What roadside breathalyzers measure |
| Urine (standard test) | 12 to 24 hours | Detects ethanol itself |
| Urine (EtG test) | Up to 72+ hours | Detects a metabolite, not impairment |
| Saliva | Up to 48 hours | Used in some workplace and roadside tests |
| Hair | Up to 90 days | Shows patterns of use, not a single night |
Typical ranges from clinical and forensic literature; individual results vary with dose, body composition, and test sensitivity.
Why the answer depends on the test
"In your system" means different things to a police officer, a probation officer, and an employer. Impairment tracks blood alcohol, which your liver burns off at a nearly constant rate of about 0.015% BAC per hour, roughly one standard drink per hour. That rate is set by liver enzymes, not by effort, so it is the same whether you are asleep, exercising, or drinking espresso.
Detection is a different question. Breath and blood tests measure alcohol itself, so they go quiet once your BAC reaches zero. Urine lags blood by an hour or two, and EtG urine tests look for a metabolite that lingers days after the alcohol is gone. Hair testing looks back months. None of the longer windows mean you are impaired; they mean you drank recently.
For driving, the only window that matters is blood and breath, and the math is unforgiving. See the exact limit where you live on the legal limits table, and remember impairment starts well below every one of them.
Roughly how long until your blood is clear
| Session | Typical peak BAC* | Time to zero |
|---|---|---|
| 2 drinks | ~0.04 to 0.06% | 3 to 4 hours |
| 4 drinks | ~0.08 to 0.11% | 6 to 8 hours |
| 6 drinks | ~0.12 to 0.16% | 8 to 11 hours |
| 8 drinks | ~0.16 to 0.22% | 11 to 15 hours |
| 10 drinks | ~0.20 to 0.27% | 14 to 18 hours |
*Peak ranges for adults roughly 55 to 90kg drinking over 2 to 3 hours; lighter bodies and female physiology land at the high end. Get your own number from the BAC calculator and the exact countdown on how long until sober.
What changes how long alcohol stays in your system
- How much and how fast you drank. Elimination is a fixed rate, so doubling the drinks roughly doubles the time to zero.
- Body weight and composition. Alcohol distributes in body water; smaller bodies and higher body-fat percentages reach higher peaks from the same drinks.
- Sex. On average, female physiology has less body water per kilogram, producing higher BAC from identical drinks.
- Food. Eating before and while drinking slows absorption and lowers the peak, but it does not speed up elimination.
- Liver health, age, and medication. Liver disease and some medications slow clearance; others (like some sedatives) multiply impairment at the same BAC.
- What does not help: coffee, cold showers, vomiting, sweating, and "sleeping it off" for two hours. Only time works.
The morning-after trap
Feeling sober is not the same as being sober. After a heavy night, BAC can stay above legal limits until mid-morning: from 0.20% at midnight you may still be near 0.08% at 8am. Hangover symptoms peak as BAC approaches zero, which is exactly when people decide they are "fine to drive." If you drank heavily last night, do the math before you touch keys, and when in doubt, do not drive. Every number on this site is an estimate, never permission.