Plan on at least one hour per standard drink before driving, and longer if you drank heavily or quickly. That is the honest answer to how long to wait after drinking to drive: your liver clears alcohol at a fixed rate of roughly 0.015% BAC per hour, and nothing you eat, drink, or do can speed it up. After a typical evening of three or four drinks, most people need four to six hours to reach 0.00%. Someone who stops drinking at midnight with a BAC of 0.16% won’t be clear until nearly 11 hours later.
Count Your Drinks Honestly First
The timeline only works if you know what you actually drank. In the United States, one standard drink contains about 0.6 fluid ounces (14 grams) of pure alcohol.1National Institute on Alcohol Abuse and Alcoholism. The Basics: Defining How Much Alcohol is Too Much That’s 12 ounces of 5% beer, 5 ounces of 12% wine, or a 1.5-ounce shot of 80-proof spirits.
Most pours don’t match those measures. A 16-ounce craft IPA at 8% alcohol is closer to two standard drinks. A generous glass of wine is often 7 or 8 ounces. A cocktail with two shots counts as two drinks. Count the alcohol in your glass, not the number of times you ordered, and when in doubt, round up.
How Long Your BAC Takes to Reach Zero
Your liver breaks down alcohol at a nearly constant pace of about 0.015% BAC per hour for most adults.2Centers for Disease Control and Prevention. About Standard Drink Sizes Some people run slightly faster, up to 0.020% per hour, but plan around the slower rate. Working from your peak BAC:
- Peak BAC of 0.05%: roughly 3.5 hours to reach 0.00%
- Peak BAC of 0.08%: roughly 5.5 hours
- Peak BAC of 0.12%: roughly 8 hours
- Peak BAC of 0.16%: roughly 10.5 hours
- Peak BAC of 0.20%: roughly 13.5 hours
These times count down from your peak, not from your last sip. Your BAC keeps rising for 30 to 60 minutes after your last drink as your stomach finishes absorbing what’s already there.
Estimating Your Peak
Peak BAC depends mainly on drink count, body weight, and biological sex. Women generally hit a higher BAC than men at the same weight and drink count because of differences in body water and metabolism. Rough estimates for drinks consumed within about an hour:
For men: two drinks at 160 lbs puts you near 0.05%; three drinks near 0.07%; four drinks near 0.09%. A 200-pound man at four drinks is around 0.08%. Five drinks at 180 lbs runs about 0.11%, and six drinks at the same weight about 0.13%.
For women: two drinks at 140 lbs runs about 0.07%; three drinks about 0.10%; four drinks about 0.13%. A 180-pound woman at four drinks is closer to 0.10%. Five drinks at 160 lbs is roughly 0.14%, and six drinks about 0.17%.
If your drinking stretched over several hours, your liver was already working during that time, so your actual peak is lower than these figures. Drink quickly on an empty stomach and your peak can run higher.
A Worked Example
A 180-pound man drinks five beers between 7 p.m. and 11 p.m. Estimated peak: around 0.11%. Subtract about 0.06% for four hours of elimination during the session (4 × 0.015%), leaving roughly 0.05% at 11 p.m. From there it takes another 3.5 hours or so to hit 0.00%, putting him at about 2:30 a.m.
A 140-pound woman drinks four glasses of wine between 8 p.m. and midnight. Estimated peak: around 0.13%. After four hours of elimination, she’s near 0.07% at midnight, and needs roughly another 4.5 hours to clear, meaning about 4:30 a.m. Four glasses of wine doesn’t feel extreme, but the math says otherwise.
What Pushes Your Wait Time Up or Down
Food in your stomach is the biggest variable you control. A substantial meal before or during drinking slows absorption and lowers your peak. Drinking on an empty stomach does the opposite.
Drinking speed matters just as much. Four drinks in one hour produces a much higher peak than four drinks spread across four hours, because your liver is eliminating alcohol the whole time in the longer session.
Medications can amplify impairment even without changing your BAC number. Sedatives, anti-anxiety drugs, sleep aids, antihistamines, and opioid pain medications all intensify alcohol’s effects. Combining alcohol with benzodiazepines is particularly dangerous, because alcohol increases their absorption and slows their breakdown. Over-the-counter antihistamines and motion-sickness medications can also compound the sedation. If a label warns against alcohol, take the warning seriously.
Individual biology plays a role too. Liver damage, certain genetic enzyme variations, and older age can all slow metabolism. None of these are easy to measure at home, which is another reason to build in a margin.
The Morning-After Trap
Sleep does not reset the clock. It has zero effect on how fast your liver processes alcohol. Stop drinking at 2 a.m. with a BAC of 0.15% and you could still be above 0.08% at 7 a.m. when you reach for the keys.
This is where a lot of impaired-driving arrests come from. The sedative effects have worn off and you feel fine, but your BAC hasn’t caught up with how you feel. If you drank heavily the night before, do the math before driving in the morning: count backward from your estimated peak at 0.015% per hour, and be honest about what you actually consumed.
What Doesn’t Speed Things Up
Nothing accelerates alcohol elimination. Coffee, energy drinks, and cold showers may make you feel more alert, but they don’t lower your BAC by a single hundredth of a percent. Eating after drinking slows absorption of any alcohol still in your stomach, but does nothing for what’s already in your bloodstream. Exercise doesn’t help either; the amount lost through sweat is negligible. Only time works.
Below 0.08% Is Not a Safe Zone
Every state uses 0.08% BAC as the per se DUI threshold for drivers 21 and older, and one state has lowered its per se limit to 0.05%.3Office of the Law Revision Counsel. 23 U.S. Code 163 – Safety Incentives to Prevent Operation of Motor Vehicles by Intoxicated Persons But 0.08% is not a safety line. Laboratory research shows driving impairment begins well below it.4National Highway Traffic Safety Administration. Lower BAC Limits At 0.02%, vision is affected. By 0.05%, coordination, steering, and emergency response have measurably declined.5National Highway Traffic Safety Administration. Alcohol and Driving
Most states also have impairment-based DUI laws alongside the per se standard. If an officer observes erratic driving, slurred speech, or poor field sobriety performance, you can be arrested and convicted at 0.05% or 0.03%. Waiting just long enough to slip under 0.08% is not a safe strategy if you’re still noticeably affected.
Personal Breathalyzers Are Not a Reliable Green Light
Consumer breathalyzers sound like a responsible check, but many are dangerously inaccurate. A study of popular smartphone-paired breath testing devices found that some underestimated BAC by 0.04% or more and failed to detect BAC at or above 0.08% more than half the time compared to a police-grade device.6National Library of Medicine. Accuracy of Consumer Marketed Smartphone-Paired Alcohol Breath Testing Devices
Fuel cell sensors are more reliable than semiconductor ones, but even the better consumer models should be read as rough indicators, not as permission to drive. A low reading from a device that routinely underestimates is worse than no reading at all.
The Safer Approach
Decide how you’re getting home before your first drink, while your judgment is still intact. A designated driver, a rideshare, a taxi, or public transit all eliminate the guesswork. Staying overnight where you are is always a better outcome than a DUI arrest or a crash.
If you do plan to drive later, stop drinking well before you need to leave and give yourself more time than the math says. Alcohol metabolism varies enough from person to person that an extra hour or two is the only reasonable hedge. If the calculation feels like a close call, it is one, and the right answer is another ride.