For most adults in the United States, the legal driving limit is a blood alcohol concentration (BAC) of 0.08%, and reaching that level takes roughly two to four standard drinks in an hour, depending on your body weight and biological sex. There is no single magic number of drinks that applies to everyone, which is exactly why the law is written around BAC rather than drink count.
What the Law Actually Measures
Every state except Utah sets the legal limit at 0.08% BAC. Utah lowered its limit to 0.05% in December 2018, and over 150 countries worldwide use 0.05% or lower as their standard. Washington state has pushed legislation to follow Utah’s lead, though the bill has not yet passed a full floor vote and is expected to be reintroduced in 2026.
Two other groups face stricter limits regardless of state. Commercial vehicle drivers are legally over the limit at 0.04% BAC, per federal regulations. And drivers under 21 fall under zero-tolerance laws in every state, meaning any detectable alcohol can result in a charge.
How Many Drinks Reach 0.08%
A “standard drink” in the U.S. contains 0.6 ounces of pure alcohol. That works out to 12 ounces of regular beer (5% ABV), 5 ounces of wine (12% ABV), or 1.5 ounces of distilled spirits (40% ABV, or 80 proof). Many cocktails, craft beers, and large pours contain significantly more alcohol than one standard drink, so what feels like “one drink” at a bar may count as two.
BAC charts published by state agencies show how body weight changes the equation dramatically when drinks are consumed over one hour:
- 120 pounds: Two drinks can put you at 0.08% to 0.09% BAC, already at or over the limit.
- 140 pounds: Two drinks typically bring you to around 0.07% to 0.08%, right at the threshold.
- 160 pounds: Two drinks reach roughly 0.06% to 0.07%. A third drink pushes you over.
- 180 pounds: Two drinks land around 0.05% to 0.06%. Three drinks will likely cross 0.08%.
- 200 pounds or more: Two drinks may keep you near 0.05%, but three drinks will approach or exceed the legal limit.
Biological sex matters too. People with a higher proportion of body fat and lower water content (which is more common in women) absorb alcohol differently, reaching higher BAC levels from the same number of drinks at the same body weight. The charts above reflect this: a 140-pound person in one group hits 0.07% after two drinks, while a 140-pound person in the other group hits 0.08%.
Why “Just Two” Isn’t Always Safe
The common advice that “two drinks is fine” is dangerously oversimplified. A person weighing 120 pounds can hit the legal limit after just two standard drinks in an hour. And in Utah, where the limit is 0.05%, a single drink is enough to put someone at 100 to 120 pounds at or over the line.
Other factors push BAC higher than the charts predict. Drinking on an empty stomach accelerates absorption. Fatigue, medications, and dehydration can amplify impairment at any BAC level. And the drinks themselves matter: a 16-ounce craft IPA at 8% ABV contains nearly twice the alcohol of a “standard” beer, so two of those pints are closer to four drinks.
How Fast Your Body Clears Alcohol
Your liver processes alcohol at a fixed rate of roughly one standard drink per hour. No amount of coffee, food, or water speeds this up. If you have three drinks in an hour and reach 0.08%, it takes approximately three hours from your last drink for your BAC to return to zero. Many people are arrested the morning after heavy drinking because their BAC is still above the limit hours later.
This also means spacing your drinks out makes a real difference. If you have one drink per hour, your body clears most of each drink before the next one arrives, and your BAC stays relatively low. Drinking three or four drinks in the first hour of the evening, then switching to water, still leaves you above the legal limit for a significant stretch of time.
Impairment Starts Before 0.08%
The legal limit is not the point where impairment begins. It’s the point where the law draws a criminal line. According to the National Highway Traffic Safety Administration, measurable driving impairment starts much earlier:
- At 0.02% BAC (often just one drink), you already experience some loss of judgment, altered mood, and a reduced ability to track moving objects or handle two tasks at once.
- At 0.05% BAC (one to two drinks for most people), coordination drops, alertness decreases, and your ability to steer and respond to emergencies is reduced. This is the level Utah considers legally impaired.
- At 0.08% BAC, muscle coordination is poor across the board: balance, speech, vision, reaction time, and hearing are all affected. Short-term memory, speed control, and the ability to detect danger are significantly impaired.
This is the reason safety organizations have pushed for lower legal limits. A person at 0.05% already has meaningfully worse driving skills than a sober driver, even though they feel fine and are technically legal in 49 states. The gap between feeling okay and actually being okay behind the wheel is where most alcohol-related crashes happen.
Practical Takeaways by Body Size
If you weigh under 140 pounds, two standard drinks in an hour will likely put you at or very near 0.08%. If you weigh between 140 and 180 pounds, two drinks will bring you into the impaired range and a third will push you over. If you weigh over 200 pounds, you have more margin, but three drinks in an hour will still approach the limit. These estimates assume standard drink sizes, consumed over one hour, with food in your stomach. Stronger drinks, faster drinking, or an empty stomach all shift the numbers higher.
The safest approach is straightforward: if you plan to drive, one drink is the most that keeps nearly everyone well below legal and impairment thresholds. Two drinks is a gamble that depends heavily on your size, your sex, what you ate, and how fast you drank. Three drinks in an hour puts the majority of adults at or over the legal limit.