How many hours after drinking can you drive? The honest answer is at least one hour per standard drink as a bare minimum, and often several hours longer, because the average person’s body eliminates alcohol at roughly 0.015 percent BAC per hour and nothing speeds that up. Three drinks can keep you legally impaired for four or five hours. A heavier night can leave you over the limit well into the next morning. There is no universal safe number, because body weight, sex, food, medications, and individual metabolism all shift the math.
Why One Hour Per Drink Is a Floor, Not a Guarantee
Your liver does nearly all the work of breaking alcohol down, and it operates at a more or less fixed speed regardless of how much you’ve had. For most people that speed is about 0.015 percent BAC per hour, with a range of roughly 0.010 to 0.020 depending on genetics, drinking history, and what’s in your stomach. A single standard drink raises most people’s BAC by roughly 0.02 to 0.04 percent. Do the division and the actual time to clear one drink is usually longer than an hour, not shorter.
A standard drink in the United States contains 0.6 ounces (14 grams) of pure alcohol. That’s a 12-ounce beer at 5 percent ABV, a 5-ounce glass of wine at 12 percent, or a 1.5-ounce shot of 80-proof liquor.1Centers for Disease Control and Prevention. About Standard Drink Sizes Anything stronger or larger counts as more than one. A 16-ounce craft IPA at 8 percent ABV is closer to two standard drinks. This is where most people’s mental math falls apart before they even start counting hours.
Here’s a practical example. Four glasses of wine over a two-hour dinner can put your BAC somewhere around 0.09 to 0.12 percent by the time you’re finishing dessert. At an elimination rate of 0.015 percent per hour, dropping from 0.09 to below 0.08 takes about 40 minutes. Reaching 0.00 takes about six hours. You will feel fine long before you are actually at zero.
A Conservative Way to Estimate Your Wait
If you want a rough number: take the number of standard drinks you had, multiply by 0.025 (a reasonable average BAC contribution per drink for a medium-sized person), and divide by 0.015. That’s roughly how many hours from your last drink to zero BAC. Six standard drinks peaking near 0.15 percent works out to about 10 hours. The formula is deliberately conservative. You should be too.
What Actually Changes Your Timeline
The one-hour-per-drink rule is an average, and several things push your real number in either direction.
- Body weight and composition. A larger person with more muscle and body water usually reaches a lower BAC from the same drinks than a smaller person, because alcohol distributes through body water.
- Biological sex. Women generally reach a higher BAC than men of similar weight from the same amount of alcohol. Women tend to have proportionally less body water and lower levels of alcohol dehydrogenase, the enzyme that starts breaking alcohol down in the stomach.
- Food. Eating before or while drinking slows absorption significantly. A full stomach can reduce your peak BAC by as much as a third compared to drinking on an empty one.
- Drink strength and speed. Carbonated and higher-ABV drinks absorb faster. Four shots in an hour produce a dramatically higher peak than four beers sipped over three hours.
- Age and liver health. Liver function declines with age, and chronic conditions or liver disease slow metabolism considerably.
Medications Rewrite the Math Entirely
Antihistamines, sleep aids, anti-anxiety medications, opioid painkillers, and even some cold medicines cause drowsiness, slowed reaction time, or blurred vision on their own. Combined with alcohol, those effects can multiply rather than just add up.2National Highway Traffic Safety Administration. Dangers of Driving After Taking Prescription Drugs or Over-the-Counter Medicines A single beer on top of a normal dose of a sedating antihistamine can impair you as much as several drinks alone. If any medication you take warns about drowsiness, treat even one drink as a reason not to drive.
The Morning After Is When Most People Miscalculate
This is where responsible adults get caught. You stop drinking at midnight, sleep six or seven hours, and drive to work at 7 AM feeling groggy but functional. If your BAC peaked at 0.15 percent around midnight, six hours only brings you down to roughly 0.06 percent by 6 AM. That’s below the legal limit in most states, but well into the impaired range. Drink more heavily, or stop later, and you can still be above 0.08 percent behind the wheel the next morning. A significant number of DUI arrests happen in the early morning hours precisely because drivers assume that sleeping counts as sobering up. It doesn’t. Only time does.
What Doesn’t Speed Up the Clock
Coffee, cold showers, energy drinks, fresh air, and exercise do not lower your BAC. They may make you feel more alert, but feeling alert and being unimpaired are two different things. Only time reduces your BAC.
Consumer breathalyzers marketed as safety tools are not a reliable substitute for waiting, either. A 2022 laboratory study testing seven consumer breathalyzers against a police-grade device found that some products underestimated BAC so severely that they failed to detect levels at or above 0.08 percent more than half the time. Only one consumer device (the BACtrack Mobile Pro) performed consistently close to the police-grade model.3PubMed Central. Accuracy of Consumer Marketed Smartphone-Paired Alcohol Breath Testing Devices Even police-grade breath equipment tends to read up to 15 percent lower than actual venous blood alcohol. A keychain breathalyzer showing 0.06 percent could mean your real BAC is 0.08 or higher.
The Legal Limits You’re Waiting to Get Below
Every state makes it illegal to drive at or above a specific BAC threshold, and you can also be charged with impaired driving below that threshold if an officer observes signs of impairment.
- Drivers 21 and older. 0.08 percent BAC in every state except Utah, which lowered its limit to 0.05 percent in 2018.4National Highway Traffic Safety Administration. Lower BAC Limits
- Drivers under 21. All states set limits at 0.02 percent or lower, and many at 0.00. A single drink can put an underage driver over.4National Highway Traffic Safety Administration. Lower BAC Limits
- Commercial drivers. Federal regulations set the limit at 0.04 percent and prohibit any detected alcohol while on duty. A first offense at or above 0.04 percent brings a one-year disqualification; a second is a lifetime disqualification.5eCFR. Subpart D – Driver Disqualifications and Penalties
Crossing these lines is a “per se” violation: the BAC alone is enough to convict. Being under the limit doesn’t guarantee safety either. Measurable impairment begins at a BAC of just 0.02 percent, and several states, including Colorado, New York, and West Virginia, have separate impairment-based offenses that can apply below 0.08.4National Highway Traffic Safety Administration. Lower BAC Limits
What Guessing Wrong Actually Costs
A first-time DUI routinely reaches $10,000 or more once you total bail, towing, fines, court fees, attorney fees, alcohol education programs, license reinstatement, and an ignition interlock device. Interlocks alone typically run $70 to $150 per month for six months to two years, and 31 states plus the District of Columbia now require them for all DUI offenders, including first-timers.6National Conference of State Legislatures. State Ignition Interlock Laws Most states also impose harsher penalties when BAC is especially high, typically at 0.15 or 0.20 percent.7National Conference of State Legislatures. Increased Penalties for High Blood Alcohol Content The biggest long-term expense is usually insurance: after a DUI, most drivers carry an SR-22 for about three years, and premiums commonly rise 70 to 90 percent during that period. Refusing a breath or blood test doesn’t help. All states except one impose separate penalties for refusal, typically an automatic license suspension, and in at least 12 states refusal is itself a criminal offense.8National Highway Traffic Safety Administration. BAC Test Refusal Penalties
The Practical Bottom Line
Given how many variables affect BAC and how badly people judge their own impairment, the reliable approach is to decide before you start drinking how you’re getting home. If you do end up calculating hours, assume your estimate is optimistic. People underestimate how much they drank, overestimate how fast they metabolize, and feel sober long before they are. When in doubt, wait longer than you think you need to. If the drinking was heavy or ended late, the safe answer to “can I drive yet” is often “not until tomorrow afternoon,” not “in a few more hours.”