The 5 best breathalyzers to confirm your blood alcohol content is low enough to drive

The best overall

The BACtrack Trace ticks every box for a personal breathalyzer: It is not too expensive, is highly accurate, warms up quickly, and displays results quickly.

Pros: Accurate, reliable, great value for price, quick to use

Cons: Requires recalibration

Our tests found the BACtrack Trace to deliver readings as precise as the more expensive, high-accuracy breathalyzers. It takes about 11 seconds to prepare for use once you turn it on, and it delivers results within just a few seconds as well, so you won't be stuck staring at the screen for long. At $100, it's a great value for the price.

The only real drawback is that the breathalyzer needs to be sent in for calibration every 6 to 12 months to maintain accuracy, depending on how frequently you use it, but this is true of virtually all breathalyzers so we can't really count it against the Trace.

The best on a budget

Don't be fooled by the low price — the AlcoHAWK offers accuracy on a budget.

Pros: Fairly high accuracy, dramatically lower price

Cons: Takes a minute to warm up, less precise, requires calibration for best results

Proof that price doesn't always reflect quality, the AlcoHAWK is a fraction of the cost of competing products but, based on my testing, delivers similar accuracy and reliability as the professional-grade breathalyzers I tried. If you're interested in having a breathalyzer on hand for the random afternoon wine tasting or dinner party, this is the one to get.

It does have a few small cons: The device takes a minute to warm up between tests which some might find mildly annoying if you're testing multiple people. Also, the results displayed on its red LED screen are rounded up to the second decimal place, so your reading won't be as exact as on other machines. But you don't need a third decimal place to determine if you're sober enough to drive or not. And we love that it rounds up instead of down, erring on the side of caution.

The best high-accuracy

The BACtrack S80 offers "police-grade accuracy" and speedy readings if you're testing several people.

Pros: Precise and reliable readings

Cons: Higher cost, requires recalibration

BACtrack describes this model — its most expensive — as having "police-grade accuracy," and all sources seem to agree. The S80 has received glowing reviews from customers and publications, and it proved its reliability and accuracy during our own tests as well.

If you're using a breathalyzer as a parent or school administrator, this is the one you should invest in for the sake of being as fair as possible. Plus, it's quick: The device warms up in under 15 seconds and gives you your reading within 3 seconds, which can be helpful if you're testing several people.

The best high-tech

The BACtrack Mobile is small, connects to your phone via Bluetooth, and provides an estimate of how long till your BAC will be 0.00%.

Pros: Compact, accurate, estimates how soon you'll be sober, easy to connect to phone, rechargable

Cons: Estimate doesn't take personal factors into account, requires a smartphone

Welcome to the 21st century: The BACtrack Mobile connects to your smartphone with Bluetooth, so it automatically logs your results, which is useful for those looking to monitor their alcohol consumption habits over time. The connection is easy and intuitive to set up and use, and the device is rechargeable so you don't have to worry about batteries.

This gadget doesn't have a display, so you do need the app to use it and see your results. If you don't have a smartphone or don't want to rely on one, this device is not the one for you. Note that also means if your phone is dead, you can't use the breathalyzer.

Based on our tests, this device is also highly accurate and comparable to other BACtrack models. And the Mobile is considerably smaller than most of the other breathalyzers on this list, which can be convenient for slipping into a purse or pocket.

Using the app also provides you with another piece of information: your "ZeroLine," which is an estimate of how soon your BAC will return to 0.00%. This can be super useful for planning the rest of your night and determining whether to drive or call a car. However, it should be noted that people process alcohol at dramatically different rates, based on their size, what they've eaten that day, and many other individual factors, so while the ZeroLine can provide you with a general timeline, you definitely want to test your BAC again before driving.

The best compact

The BACtrack C6 Smartphone Keychain Breathalyzer is smaller than a pack of gum.

Pros: Super compact, convenient, optional smartphone connect, fairly affordable

Cons: Slightly lower accuracy, requires recalibration

Conveniently, the C6 is designed as a keychain, so you'll always have it on-hand when you're wondering if you're ready to leave a dinner party or should hang out for a while longer. Even smaller than the BACtrack Mobile, the C6 also estimates your ZeroLine to tell you how long till you're likely at 0.00%.

What's more, it has the ability to connect to your phone in order to store your reading, too. However, on this model, this feature is optional — if your phone is dead or you just don't want to use it, the keychain breathalyzer functions on its own, displaying your BAC reading on its screen.

Also convenient is the fact that the C6 warms up quickly, in just about five seconds. And being one of the cheaper products we tested, it's good value for the money. The trade-off is that the C6 isn't quite as accurate as the more professional devices, but the difference is marginal and unlikely to change anything in practice.

Our testing methodology

I personally tested each device on this list to get an idea of what it's like to use and to judge its accuracy. I drank exactly one standard drink (5 oz of wine) then after 30 minutes measured my BAC on each device and noted each reading. I measured again another 30 minutes later. Then, I repeated the whole process the next day (to make sure we didn't have any flukes).

I then evaluated the data to see if any outlier readings were statistically significant. The products we deemed most accurate and reliable were those with the fewest anomalous readings and most consistency with other devices.

	Test 1 - 30 mins	Test 1 - 1 hour	Test 2 - 30 mins	Test 2 - 1 hour
BACtrack Trace Professional Breathalyzer	0.036	0.025	0.023	0.017
BACtrack S80 Professional Breathalyzer	0.033	0.025	0.024	0.017
BACtrack Mobile Smartphone Breathalyzer	0.037	0.027	0.025	0.017
AlcoMate Premium AL7000 Professional Breathalyzer	0.039	0.029	0.026	0.02
AlcoHAWK Ultra Slim Breathalyzer	0.04	0.03	0.03	0.01
BACtrack C6 Smartphone Keychain Breathalyzer	0.033	0.024	0.021	0.015

Note: Despite drinking the same, standardized amount for Test 1 and Test 2, my BAC reading was different between the days. This could be from a variety of factors, like what I ate and how long beforehand. What's important is comparing Test 1's tests among the different breathalyzer, and seeing if those discrepancies were repeated with the same brand on Test 2.

What to look for when buying a breathalyzer

There are only a handful of companies that make breathalyzers for the general public (which is why we include multiple devices by BACtrack) but even so, the products on the market have some significant differences. When buying a personal breathalyzer, consider:

Price: The cheapest product we tried was about $40 and the most expensive $131. Generally, the more expensive breathalyzers do tend to be more accurate and reliable, but you don't need the same level of detail for recreational use as, say, a police officer would. If your reading is at all borderline or uncertain, you can always just wait a little longer and test yourself again later.

Accuracy and reliability: Virtually all major breathalyzer manufacturers  claim "professional" or "police-grade" accuracy, so it can be difficult to determine which devices actually deliver on that claim. Since accuracy is crucial in staying safe behind the wheel, we conducted trials to test the accuracy of each device so that we can tell you which ones live up to their price tag. And we found price does not denote reliability.

Result readability: Some breathalyzers will display your BAC right on the device, while others have an optional or mandatory Bluetooth smartphone connection. The latter can be useful if you want to store your results in a log. But if you don't have or don't want to use a smartphone, skip this feature and be sure to get a standalone device.

Calibration and charging: Most breathalyzers need to be sent back to the manufacturer for calibration after 6-12 months in order for the device to continue to read BAC levels accurately. If you'd rather replace the sensor yourself, pick a model for which that's possible. Also, note what kind of batteries the device takes and if it's rechargeable or not.

What else we considered

What we don't recommend

AlcoMate Premium AL7000 Professional Breathalyzer ($131): The AlcoMate, like the other devices on this list, is slim and simple to use; however we found its accuracy a bit questionable, especially considering the price. Instead of sending it back to the manufacturer for calibration, however, you can replace the sensor yourself, which may be appealing for some.

FAQs

Do personal breathalyzers really work?

First, it's worth acknowledging that breathalyzers are fallible and results can be affected by operator error (aka you) as well as technical issues. This is partially why breathalyzer BAC readings, on their own, are considered inadmissible trial evidence in some states. But high readings from a personal device should never be shrugged off as a false positive — if there's any indication that you're not sober, don't get behind the wheel.

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How do you use a breathalyzer?

Timing matters, a lot. The manufacturer's instructions for all the products we tested say to wait about 20 minutes after eating and drinking to use the breathalyzer since it takes time for alcohol to be absorbed into a person's system after consumption. But because people's bodies metabolize alcohol at different rates, measuring at 20 minutes isn't always going to produce the most accurate results. Depending on your physiology, what else you've had to eat or drink, and timing, among other factors, your BAC could very well keep increasing even after a 20-minute wait.

"I can't give you a fixed number [of how long after a drink to measure], because depending on how much you drank, your alcohol content is going to keep going up," Sovndal said. "If I drink 5 beers and 2 tequila shots and then measure it, I could still be on the uprise. It might not flatten out for another hour."

To be safe, measure your levels after 30 minutes and then again after 60. If your BAC is higher at the second reading, wait another 30 minutes before taking another reading.     

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Do breathalyzers work for everyone?

Certain groups of people are more likely to blow false positives, namely diabetics and those on low-calorie or ketogenic diets, as the presence of ketones in one's breath will interfere with the reading.

Our sources

In addition to research, for this article we spoke with Dr. Shannon Sovndal, MD, FACEPS, who is a board-certified doctor in emergency medicine and emergency medical services (EMS) in Boulder, CO. He is a fellow of the American College of Emergency Physicians and has worked extensively in pre-hospital medicine, the fire service, and tactical medicine. He is currently the medical director for multiple EMS agencies and is the author of three books including his most recent "Fragile."