Do Personal Breathalyzers Work?

personal BreathalyzerDrunk driving is problem in the United States, and has been ever since the advent of the automobile. A number of companies have come up with solutions to help reduce the number of drunk drivers on the road. There are “drunk cabs”—a free service that takes intoxicated people home safely. Designated drivers are also an option, as is using Uber or Lyft. Then there are personal blood alcohol calculators. The third, BAC (blood alcohol content) calculators, are increasingly raising people’s eyebrows. Some device manufacturers have even paired their technology with your smart phone. While the concept of a personal breathalyzer is incredibly creative, is it effective?

Personal Breathalyzers are accessible, but are they reliable?

Before there were personal breathalyzers, there have been websites to help drinkers learn their limits. The idea is that if you know your limit before you go out, you won’t over-consume. Of course, that’s not always how it works out. Some inventive companies recognize that self-control isn’t everyone’s forte, and have new solutions.

To help those who have drunk a bit more than they meant to, several companies have produced a portable personal breathalyzer. The intent is simple and good-willed: to make sure no one who has had too much to drink ends up getting behind the wheel of a car.

Since they are portable, you can take these BAC testers out to the bar in your back pocket or purse. Then, you can use it when you’re getting close to calling it a night. In a perfect world, you’d see your BAC and make an informed decision as to whether or not you are OK to drive. In practice, however, these devices should never be used to gauge whether someone is safe to drive a car. The only ‘safe’ strategy to avoiding a DUI is to plan your route home prior to beginning your night, whether it is a taxi, a designated driver or mass transit.

The reliability of personal breathlyzers is up for debate. The devices are portable, so they’re relatively sturdy on the outside. However, they contain delicate, calibrated parts inside. If the internal parts are jostled too hard, the device may not work properly, and therefore not entirely reliable. Also, consider that this device is used by someone who has been drinking, so usage may not be perfect every time. Simply put: there is room for error.

Factors a personal breathalyzer can’t adjust for:

Most of a personal breathalyzer’s function is fundamental science. They aren’t complex devices. The way they calculate your BAC can often be incorrect. Here are some things that can screw up a breathalyzer’s reading:

Lung Capacity:

Breathalyzers measure the concentration of alcohol on your breath. If you have a higher than average lung capacity, then one drink will register differently for you than it will for someone with a normal lung capacity. The more air you have in a breath, the more diluted the alcohol will be.

Body Weight:

Similar to lung capacity, body weight has a definite affect on your personal breathalyzer results. Let’s say you weight 210 pounds and have 2 beers. Your BAC reading would be higher than someone who weighs 120 pounds and also had two beers.

Health and Lifestyle:

best personal breathalyzer Some chemicals in your body can affect the reading of a breathalyzer too. For that reason, smokers and people with diabetes or liver conditions are at risk for inaccurate readings.


Professional-grade breathalyzers used by law enforcement are expensive devices. They are calibrated regularly by trained professionals, and are accurate within a very narrow range. Personal breathalyzers can cost as little as $20, and rarely — if ever — enjoy such careful calibration. As a result, the results you might get from a personal breathalyzer can vary wildly. There’s a reason they say ‘for novelty purposes only.’

The Best Personal Breathalyzers

Before we compare personal breathalyzers, say it with us one more time: even the best personal breathalyzer isn’t a guarantee that you’re good to drive.

  • The BACtrack S80 is one of the most accurate personal breathalyzers on the market. Someone once drank in a police station (for the sake of safe, controlled research) and deemed that not only is this personal breathalyzer the clear winner, but that it was the only contender. Keep in mind, that ‘most accurate’ still has a margin of error of .005, which can be the difference between DUI and not.
  • If novelty is more important to you than accuracy (the BACtrack S80 ran $135), there are other options. A keychain breathalyzer called BACtrack Keychain is only $30. It comes in fun colors and is much more convenient to carry around. However, this model is much less accurate, running a margin of error of .02%.
  • Maybe you’ve made it this far and are thinking, there’s got to be an app for this. Alas, there is, and it’s BACtrack Mobile. Our third pick meets in between the two previous choices, but also offers a unique feature. BACtrack Mobile will take your test results and estimate when you’ll be back to 0.

We’ve said it a few times that personal breathalyzers are not entirely accurate (they’re not). However, they might be just the tool you need to convince a stubborn friend to not get behind the wheel of a car after a night out of drinking.

The difference between personal breathalyzers and Blood Alcohol Calculators matters

Consumers use personal blood alcohol calculators based on the premise that they will accurately tell the user when they are too inebriated to drive. The problem is that there is often a disconnect between how the blood alcohol calculator and the personal breathalyzer works. Blood Alcohol Calculators (such as B4UDrink) forecast your blood alcohol, given variables such as height, weight, age, and drinks consumed over a given period. Breathalyzers measure your blood alcohol, via the amount of alcohol vapor you exhale. Unfortunately, there are many factors at play, causing personal breathalyzers to be often woefully inaccurate.

For this reason, a personal breathalyzer might be a fun toy, but just because it say that you’re good to drive, doesn’t make it so. Passing a personal breathalyzer test doesn’t mean that you won’t get a DUI, or worse. If you’re using a personal breathalyzer to see if you’re too drunk to drive, that means you’re too drunk to drive.

It’s everyone’s responsibility to take precautions and not leave it up to chance or to inaccurate instruments. If you’re planning on drinking, always have a plan for how you will get home prior to drinking – a ride from a friend, a cab or a designated driver. It’s the only surefire way to avoid a DUI.

More Drunk Driving Resources

Drunk driving fatalities are on the rise. That’s alarming, and we want to help. We support Alcohol Awareness Month, but know that awareness is a year-round effort. If you need help, here’s some information about MADD. If you have a DUI, here’s what you need to know about SR-22’s, and insurance companies that specialize in working with high-risk drivers.

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