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BAC vs. BrAC: What’s the Difference?

BAC vs. BrAC: What’s the Difference?

Drivers who were pulled over by a police officer for drinking and driving may have heard of the acronyms BAC and BrAC, but don’t know what they mean. We’re going to explain how they’re measured and what can impact the results. Drivers with any questions should have them answered here, but if any readers still have questions, an Intoxalock state specialist can help answer them.

The two methods of measuring alcohol contents in the body are similar, but there are key differences. Let’s break it down.

What is Blood Alcohol Content (BAC)?

This is a measurement of alcohol intoxication. If someone has a BAC of .10 or one-tenth of a percent, this means that they have .10 grams of alcohol per 100 ml of blood or one-part alcohol for every 1,000 parts of blood in their system. In most states, .08 is considered legally intoxicated, anything above .40 is potentially fatal. BAC alcohol can be measured with urine or blood tests or extrapolated from a breathalyzer test.

What is Breath Alcohol Content (BrAC)?

BrAC also measures the amount of alcohol in your system, but it does so by measuring alcohol in your exhalations. When you drink alcohol, it’s absorbed into your bloodstream and carried onward to your brain and lungs. Thus, alcohol will be in your breath when you exhale after drinking. A BrAC device will measure the amount of alcohol in your breath and use it to estimate your Blood Alcohol Content. When using an ignition interlock device (IID) to measure BrAC, even small amounts of alcohol can result in a failed test.

BrAC is used to get to Blood Alcohol Content, which is measured using blood or urine tests.

Know the Legal BAC Limit and Rules

Are you aware of the legal BAC in your state? You should be aware of the rules and regulations regarding drinking and driving in your area, so you can avoid being caught for DWI, DUI, OUI, or OWI. There is no real difference between DUI, DWI, and OWI - different states simply have different terms for alcohol-based offenses. In many states, you can get a DUI while driving vehicles that aren't cars!

There are many guidelines and BAC charts available regarding how many drinks you can have and still be under the legal limit for DUI, OUI, DWI, or OWI, like one drink per hour, but these guidelines are general and don’t account for all of the differences in body type and metabolism. While the legal BAC limit is a standard measurement, the way alcohol impacts different bodies and personalities is anything but standard. The best way to avoid driving while intoxicated is to stay sober if you’re driving, or find an alternative way to get home if you’re unsure you can drive safely.

Each time anyone is pulled over or stopped on suspicion of DUI, DWI, OUI, or OWI, the officer may request a test. This can include a field sobriety test, a breathalyzer test, and a blood or urine test. Breathalyzer tests and blood or urine tests are all testing for the percentage of alcohol present in the body. In every state but Utah, the legal BAC limit is .08 percent. In Utah, the legal limit is .05 percent.

How is BAC Measured and What Impacts Results?

Blood alcohol content is measured via a blood, breath, or urine test. It measures the amount of alcohol per 1,000 parts of blood. A BAC of .08 (.05 in Utah) is legally impaired. However, people start to feel the effect of alcohol at just .02 percent BAC. Judgment is impaired, and you are easily distracted and not able to keep up with tasks.

Many things can impact your BAC and how you metabolize alcohol, such as:

Drinking on an empty stomach

With nothing to absorb it, alcohol will hit your system fast. If your stomach is full of food, it helps keep the alcohol you drink in your stomach longer, preventing it from spreading as quickly through your bloodstream. This is why those who drink on an empty stomach feel the effects of alcohol more quickly.


Everyone metabolizes alcohol differently, but spreading out your drinks throughout the night will keep your BAC lower than if you drank them in a short time.


Many people advocate alternating water with alcoholic beverages. Not only does this help you stay hydrated, but it also forces you to space out your drinks. This can help keep your BAC within a safe range.

Breathing pattern

Holding your breath or hyperventilating (breathing very rapidly) can impact your test results.


Prescription medications or other recreational drugs can interact with alcohol and cause you to be more impacted by drinking.

How is BrAC Measured and What Can Impact Measurement?

Breath alcohol content is typically measured by a breathalyzer or ignition interlock device (IID). It measures the amount of alcohol in the air you breathe out and uses that to determine your breath alcohol content.

When you have an ignition interlock device installed, you’ll need to test your BrAC and pass in order to start your car. Many factors can impact your results. Of course, drinking is one, but other benign activities can impact your rating too, so it’s best to be careful. Here are some common things that impact test results:

Mouthwash or breath sprays

Mouthwash products and breath sprays often contain a small amount of alcohol, and this can impact your test results. Since it’s going directly into your mouth and then you are breathing out to test, your BrAC may register higher on the device.

Hand sanitizer

Most brands contain alcohol in small amounts as a cleaning agent, which could impact your test results.

Perfumes and colognes

Wait after applying your usual cologne or perfume before you test. Taking the test too soon could cause a potential issue.

Liquid cold medicine

Being sick is no fun and you should definitely take medicine when needed. However, wait 10 to 15 minutes after taking cold medication before testing your BrAC.

Category: Drunk Driving

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