Whether you can drive after one shot depends on your body and your state, but the honest answer is this: a single 1.5-ounce shot of 80-proof liquor will usually leave you below the 0.08% legal limit, yet it still impairs your driving in ways you can be arrested for. “Under the limit” and “safe to drive” are not the same thing.
What Actually Counts as One Shot
A standard drink, by federal definition, is any pour containing 0.6 fluid ounces (14 grams) of pure alcohol.1National Institute on Alcohol Abuse and Alcoholism. What Is a Standard Drink? Poster For distilled spirits, that comes out to 1.5 fluid ounces of 80-proof liquor at 40% alcohol by volume.2Centers for Disease Control and Prevention. About Standard Drink Sizes
Real-world pours often aren’t standard. A generous bartender or a home-mixed cocktail can hold two or three standard drinks in one glass. A Long Island Iced Tea typically contains four or five shots on its own. So before you decide whether you’ve “only had one,” check what was actually in the glass.
What One Shot Does to Your BAC
For most adults, a single standard shot on a relatively empty stomach produces a blood alcohol content somewhere between 0.02% and 0.04%. Where you land inside that range depends on several things. Body weight matters most, because alcohol disperses through body water; a 200-pound person reaches a lower BAC than a 130-pound person after the same drink. Biological sex plays a role, with women generally reaching higher BAC levels than men of the same weight. Food in your stomach, hydration, and how quickly your liver processes alcohol all shift the number.
Your body clears alcohol at roughly 0.015% BAC per hour. One shot takes about one to three hours to fully metabolize.
Impairment Starts Below the Legal Limit
The National Highway Traffic Safety Administration has documented measurable driving impairment well below 0.08%. At 0.02% BAC, your ability to track a moving object declines and your capacity to handle two tasks at once drops off.3National Highway Traffic Safety Administration. ABCs of BAC Vision is affected for all drivers at that level.4National Highway Traffic Safety Administration. Alcohol and Driving By 0.05%, judgment is impaired, steering becomes harder, and your response in emergencies is reduced.
You probably won’t feel drunk after one shot. That’s the trap. Your brain is already processing road information more slowly than it was before you picked up the glass, and the impairment sits below the threshold of conscious awareness. People consistently overestimate their own sobriety after drinking.
The 0.08% Limit Isn’t a Safe Harbor
Congress made 0.08% BAC the national per se standard for impaired driving in 2000. Under 23 U.S.C. § 163, any state that fails to enforce a 0.08% law faces a reduction in federal highway funding.5Office of the Law Revision Counsel. 23 USC 163 – Safety Incentives to Prevent Operation of Motor Vehicles by Intoxicated Persons Every state uses 0.08% or lower. One state has already dropped its limit to 0.05%.
The important thing to understand is what that number does and doesn’t mean. It’s a per se limit, which means the BAC alone is enough to convict you. It is not a ceiling on prosecution. Virtually every state also has an impairment-based DUI law that lets an officer arrest you at any BAC if your driving shows you were too impaired to operate a vehicle safely. Weaving across lanes, missing a stop sign, and slurred speech during the stop can support a DUI charge even at 0.03%.
By driving on public roads you’ve also already agreed, under your state’s implied consent law, to submit to a chemical test if an officer has probable cause to suspect impaired driving.6National Highway Traffic Safety Administration. BAC Test Refusal Penalties Refusing doesn’t neutralize the risk. Nearly every state imposes a separate administrative license suspension for the refusal, and the refusal itself can be used as evidence against you.
When One Shot Is Automatically Too Much
The 0.08% figure doesn’t apply to everyone. Two groups face limits that a single standard shot can push you past on its own.
Commercial drivers. The federal BAC limit while operating a commercial vehicle is 0.04%. One standard drink can realistically put a smaller commercial driver at or above that line. Federal regulations disqualify CDL holders for a full year after a first DUI conviction, and this applies even when you were driving your personal car at the time. A second DUI-related offense results in a lifetime disqualification from operating commercial vehicles. Refusing a breathalyzer triggers the same one-year CDL disqualification as a conviction.7eCFR. 49 CFR 383.51 – Disqualification of Drivers
Drivers under 21. Every state has enforced zero-tolerance laws since 1998, setting BAC thresholds below 0.02% for underage drivers.8National Highway Traffic Safety Administration. Zero-Tolerance Law Enforcement A single sip of beer, let alone a shot of liquor, can trigger a violation.
One more boundary worth knowing: national parks, military bases, and other federal lands operate under 36 CFR § 4.23. The 0.08% limit applies there, but if the surrounding state has a stricter limit that stricter limit controls, and you can also be charged for any degree of impairment that makes you incapable of safe operation, regardless of BAC.9eCFR. 36 CFR 4.23 – Operating Under the Influence of Alcohol or Drugs A federal DUI conviction can also be reported to your home state’s DMV.
The Safer Move
The only BAC that guarantees you won’t face a DUI charge is 0.00%. If you’re going to drink, separate the drinking from the driving before the first pour: pick a designated driver, plan on a rideshare or taxi, use transit if it’s available, or stay put until the alcohol is gone. Given that your body clears roughly one standard drink per hour, waiting isn’t complicated math. It’s just waiting.
Waiting “until you feel sober” is not the same thing. The impairment shows up before the feeling does, and by the time you feel fine to drive, you may already have been fine to drive for a while, or you may not be there yet. The clock is more reliable than the feeling.