Drinking and driving is never a good idea, no matter how much experience you have behind the wheel. Alcohol can numb your senses, slow your reflexes, and cloud your judgment, increasing the risk of a car crash.
But how many drinks does it take to reach this limit—and how can you tell when you’ve crossed the line? Let’s find out.
What Is BAC?
BAC, short for blood alcohol concentration, is the amount of alcohol in your bloodstream. This measurement is expressed as a percentage and calculated in grams of alcohol per 100 ml of blood. Therefore, a 0.08% BAC—the legal limit to drive a vehicle in the U.S.—would mean blood that is 0.08% alcohol by volume.
Also referred to as blood alcohol content or blood alcohol level, BAC ranges from 0.0% to 0.4% or higher. Based on its value, police officers and other authorities can determine whether a driver is impaired. As this percentage increases, so does the level of intoxication.
How Do Different Levels of Blood Alcohol Content Affect You?
Alcohol depresses the central nervous system, affecting cognitive function, behavior, and motor skills. Its impact is more or less pronounced, depending on how much you drink, how quickly your liver can process it, and other factors, such as your sex and body weight.
That said, here are some of the common physical and mental effects of different BAC levels:
- 0.0% BAC: There is no alcohol in your system.
- 0.02% BAC: You may experience a slightly altered mood, feelings of relaxation, and mildly impaired judgment. To others, you are likely to appear normal.
- 0.05% BAC: You may begin to feel uninhibited. You’re no longer capable of making sound decisions, and your alertness is reduced. To others, you’ll likely appear talkative and outgoing.
- 0.08% BAC: You may experience reduced muscle coordination, along with significant impairment in judgment, reasoning, and decision-making.
- 0.1% BAC: You’ll likely have slower reaction times and significantly impaired thinking. Slurred speech is also common. To others, you may appear visibly intoxicated—overexuberant, uncoordinated, or sloppy.
- 0.15% BAC: You might experience an altered mood, loss of coordination, and difficulty balancing and controlling muscle movements. Nausea and vomiting may occur, too.
- 0.15% to 0.3% BAC: You’re likely to be significantly drowsy and confused. Vomiting is common at this level of BAC.
- 0.31% or higher: You are at serious and immediate risk for alcohol poisoning, which can be fatal. At this stage, you are likely to experience vomiting, loss of consciousness, coma, or even death. About 50% of people with a BAC of 0.31% or higher lose their lives due to respiratory arrest.
Be aware that when it comes to driving, no amount of alcohol is safe. This substance affects everyone differently, and even a small amount in your system can have serious side effects, depending on your body’s response, weight, sex, and whether there was food in your stomach when you drank the alcohol.
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What Is the Legal Blood Alcohol Level in California?
California has strict laws against drunk driving, but how they apply can vary based on your age, the type of driver’s license you hold, and whether you’re transporting passengers. Here’s a look at the different legal limits that apply in California.
| Traffic Offense | Vehicle Code | Legal Limit for BAC | What It Means |
|---|---|---|---|
| Zero Tolerance | VC 23136 | 0.01% | Individuals under 21 are prohibited from driving with any alcohol in the bloodstream. |
| VC 23154 | 0.01% | This requirement also applies to drivers on DUI probation, regardless of age. | |
| Standard DUI | VC 23152(b) | 0.08% | Non-commercial adult drivers may not operate a vehicle if their BAC is 0.08 or higher. |
| Commercial DUI | VC 23152(d) | 0.04% | Commercial drivers must maintain a BAC below 0.04% while operating a vehicle. |
| Rideshare DUI | VC 23152(e) | 0.04% | Your BAC cannot exceed 0.04% while transporting a passenger for hire. |
The penalties for breaking these rules include license suspension, fines, probation, or even jail time.
The 0.08% limit was enforced in California on January 1, 1990, down from 0.10%, in an attempt to reduce alcohol-related accidents. At the time, California became the fourth state to adopt the lower threshold, following Oregon, Utah, and Maine.
How Many Drinks Does It Take to Reach a 0.08% BAC?
According to the University of Arizona, most people will reach or exceed the 0.08% threshold after drinking two to four drinks in one hour. Note that, in the U.S., a standard drink means a five-ounce glass of wine (12% alcohol), a 12-ounce can of beer (5% alcohol), or a shot of distilled spirits (40% alcohol).
With that in mind, let’s see how many drinks it takes to reach a 0.08% BAC based on your gender—and what to expect in terms of impairment from alcohol. Because men and women process alcohol at different rates, we’ve provided two separate charts.
| Estimated BAC by Number of Drinks (180-pound man, 1 hour) | ||
|---|---|---|
| Drinks Consumed in 1 Hour | Estimated BAC | Risk Level |
| 1 | 0.02% | Possibly impaired |
| 2 | 0.04% | Possibly impaired |
| 3 | 0.06% | Somewhat impaired |
| 4 | 0.08% | Legally impaired (DUI) |
| 5 | 0.11% | Legally impaired (DUI) |
| 6 | 0.13% | Legally impaired (DUI) |
| 7 | 0.15% | Highly impaired, potentially fatal consequences |
|
*Subtract 0.015 for each hour after drinking. Source: National Highway Traffic Safety Administration (NHTSA) | ||
| Estimated BAC by Number of Drinks for the Average Woman (140 pounds) | ||
|---|---|---|
| Drinks Consumed in 1 Hour | Estimated BAC | Risk Level |
| 1 | 0.03% | Possibly impaired |
| 2 | 0.07% | Somewhat impaired |
| 3 | 0.11% | Legally impaired (DUI) |
| 4 | 0.13% | Legally impaired (DUI) |
| 5 | 0.16% | Highly impaired, potentially fatal consequences |
| 6 | 0.19% | Highly impaired, potentially fatal consequences |
| 7 | 0.23% | Highly impaired, potentially fatal consequences |
|
*Subtract 0.015 for each hour after drinking. Source: National Highway Traffic Safety Administration (NHTSA) | ||
Based on these figures, a 140-pound woman can become legally intoxicated after drinking two to three beers or whiskey shots in one hour. By comparison, a 180-pound man can drink up to four beers or whiskey shots in an hour before becoming legally intoxicated.
Key Ways to Calculate Blood Alcohol Content
Alcohol levels can be measured through breath, blood, or urine tests, each varying in accuracy. Mobile apps and BAC calculators can be helpful, but they offer only rough estimates.
Here are the methods available to calculate blood alcohol content:
Manual Estimation
The Widmark formula is an equation that estimates BAC based on body weight, gender, and the amount of alcohol consumed over a given period. The formula is:
BAC = [Alcohol consumed in grams / (Body weight in grams × R)] × 100
*“R” indicates the alcohol distribution ratio—typically 0.55 for females and 0.68 for males.
While Widmark’s formula is useful for rough estimates, it is not exact. It doesn’t take your body’s unique absorption rate into account. Plus, it just isn’t practical. Many people don’t know how many grams of alcohol they have consumed or will consume.
BAC Charts
BAC charts can be found all over the internet. They are often based on the Widmark formula, providing quick estimates of blood alcohol concentration. One example is the chart featured in the California Driver’s Handbook. (Shown below.)
As with the Widmark formula, this estimation is not exact, and can’t be relied on to determine whether you’re safe to drive or over the legal limit. Plus, many drinks sold at bars and restaurants may not conform to the “standard” drink sizes assumed here.
Online BAC Calculators
Free tools like the University of New Mexico’s BAC Estimator, Alcohol.org’s BAC Calculator, and Drinkfox allow you to estimate your blood alcohol concentration online. This option is handy and portable, but the results are only rough estimates.
Mobile BAC Tracking Apps
You can use apps like AlcoTrack, DrinkControl, Alcohol Check, or similar apps to estimate your BAC. While these apps aren’t exact, some include features like drink tracking, safety reminders, and real-time alerts, which may help some people drink more safely.
Breathalyzers
These portable devices analyze the alcohol content in your breath (BrAC) using the standard 2,100:1 ratio. Simply put, the amount of alcohol in 2,100 milliliters of breath is thought to equal that in one milliliter of blood. Fast and relatively accurate, breathalyzers are widely used by police officers during traffic stops. You can also purchase your own breathalyzer. While keychain versions are not accurate, portable digital options provide reliable results and can be as inexpensive as $50.
Blood Tests
Blood tests are considered the most accurate way to determine BAC because they directly measure alcohol concentration in the bloodstream. They’re often used to confirm or challenge breathalyzer results, as well as for medical purposes.
Urine Tests
Law enforcement officers may order a urine alcohol test to determine whether someone has consumed alcohol within the past 12 to 24 hours – or up to 80 hours, depending on the type of test used. They are usually very sensitive and can detect alcohol that a breath test may not pick up.
None of these methods is 100% accurate, but some are reliable enough for authorities to take action. For example, if a breathalyzer test indicates that your BAC is above 0.08%, you’ll likely be arrested for driving under the influence. Later, you may contest the result in court, but you’ll still face immediate consequences.
How to Lower Blood Alcohol Content
You might have heard old wives’ tales about sobering up quickly—like eating a fatty meal, drinking coffee, or taking a cold shower—but these are just myths. The liver metabolizes more than 90% of the alcohol you consume, and there isn’t much you can do to make it work faster.
The only thing that can lower your blood alcohol content is time. However, there are steps you can take to reduce the effects of alcohol and prevent your BAC from rising further once you’ve had a drink or two.
- Monitor your drinking: Stick to standard drink sizes so you can better monitor your alcohol intake and stay in control. Try not to exceed a set limit that works for you.
- Know your sweet spot: If you plan on drinking, aim to keep your BAC below 0.055%. This is the so-called “green zone,” where most people feel social and relaxed without being intoxicated. Use a BAC chart or online calculator to determine how many drinks you can have before reaching a 0.055% BAC.
- Stay hydrated: Drink one glass of water for every glass of wine, beer, or whatever alcoholic beverage you consume. This habit can make it easier to pace yourself and avoid dehydration, a common side effect of alcohol.
- Avoid smoking: This is easier said than done, but try to cut back on smoking when drinking alcohol. For example, if you’re attending a special event, keep yourself busy by talking with others or dancing. According to scientific research, nicotine can amplify the pleasurable effects of alcohol and, consequently, increase drinking.
- Sip on low-alcohol drinks: Choose beer, hard seltzer, wine, or other low-alcohol drinks over spirits and liqueurs. The latter are higher in alcohol and easier to consume quickly, which increases the risk of intoxication.
- Be wary of cocktails and mixed drinks: These beverages may contain multiple servings of alcohol in a single glass, making it hard to control your intake. For example, a martini contains about two shots of alcohol, while a Long Island iced tea is equivalent to three standard drinks. Plus, you might end up drinking more than you realize because their sweetness can mask the taste of alcohol.
- Steer clear of alcohol if you’re still in your teenage years. The Centers for Disease Control and Prevention (CDC) warns that teens are more sensitive to the effects of alcohol and face a higher risk of being involved in a crash than adult drivers with the same BAC—even when it’s below the 0.08% threshold. Plus, in California it’s illegal for anyone under 21 to drive with a Blood Alcohol Concentration (BAC) of 0.01% or higher.
Can You Go to Traffic School for a DUI?
California drivers can attend traffic school to keep points off their license, but this option is available only for minor offenses like running a stop sign or failing to yield the right-of-way. DUI violations don’t qualify for traffic school.
If you’re pulled over for driving under the influence, the court may require you to complete an alcohol education program. These courses vary in length from 12 hours to 30 months, depending on your age, BAC level, and whether you’re a first-time or repeat DUI offender.
However, if you already have points on your license from a DUI, taking traffic school for other infractions can help you prevent license suspension. You may go to traffic school for dozens of other violations, from distracted driving to crossing a solid white line or following too closely. Completing the course will hide one point from your public driving record, which means insurance companies won’t see it—and your auto insurance rates are less likely to increase.
Read: How Traffic School Works
Why Choose Best Online Traffic School?
At Best Online Traffic School, we offer a quick online course you can take at your convenience from any device, including your smartphone. We’re a DMV-approved traffic school, and are accepted by all state courts.
Traffic school has never been easier. Study anytime from anywhere, take breaks as needed, and access the course materials during the final exam. 99.9% of our students pass on the first try.
Our course is engaging and easy to follow, featuring videos, practice tests, and other resources for a seamless learning experience. Here’s what you’ll get:
✅ Audio read-alongs in English, Spanish, and Chinese
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We’re so confident in our learning method that we won’t charge you a penny until you pass. Take our traffic school course for free, complete it in one sitting or over several sessions, and pay only when you’re done.
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FAQs about Blood Alcohol Content
Looking for more information on how BAC affects your driving—or your DMV record? Below are the answers to some frequently asked questions.
Is California a zero-tolerance state?
Yes, it is, but its zero-tolerance laws apply only to underage drivers and those on DUI probation. For these groups, driving with any amount of alcohol (0.01% or higher) in the bloodstream can result in license suspension, fines, and other penalties.
What’s the difference between a DUI and a DWI in California?
California law doesn’t distinguish between driving under the influence (DUI) and driving while intoxicated (DWI). These terms are used interchangeably and refer to the same offense.
Is 0.08% the legal limit in all states?
No, it is not. While 0.08% BAC is the federal standard adopted by most states, Utah has a legal limit of 0.05%.
Additionally, most states impose harsher penalties for drivers with BAC levels above the 0.08% threshold, such as 0.15% in Alabama, 0.17% in Colorado, and 0.20% in Massachusetts. See this list of DUI laws and limits in each state.
What is the breathalyzer limit in California?
The breathalyzer limit in California is the same as the BAC limit: 0.08% for drivers aged 21 or older, 0.04% for commercial drivers, and 0.01% for teens and drivers on probation.
Is there a fine for a DUI in California?
Yes, there is. Drivers convicted of a DUI must pay a base fine ranging from $390 to $1,000, plus penalty assessments and court fees. If you’re under 21 and get caught driving while intoxicated, you may have to pay a $100 fine.