- Home breathalyzers test your blood alcohol content to confirm sobriety before driving.
- We tested 6 portable breathalyzers for accuracy, reliability, and ease of use.
- Our top choice, the BACtrack Trace Professional Breathalyzer, is quick and highly accurate for $100.
It’s been a couple of hours since your last drink. You feel fine, but what if your judgement is off?
Home breathalyzers – much like, and in some cases the same, ones used by law enforcement during traffic stops – can be a great safeguard for safe driving when used appropriately. These devices essentially run an alcohol breath test, measuring the chemical composition of your breath to generate an estimate of your blood alcohol content (BAC).
In the U.S., the legal BAC limit for drivers over 21 is 0.08% – about two to three standard drinks (that’s 5 ounces of wine or 12 ounces of beer). (For those who are underage, limits change by state but are typically .00 to .02%.)
Let’s be clear: Driving while under the influence of alcohol is never okay. But it is possible to, say, have one drink with dinner, or cut yourself off after a few at a party to get behind the wheel a couple of hours later.
But because a lot of factors go into how quickly alcohol leaves your system, it’s smart to confirm your BAC: “You might feel like you’re okay,” Shannon Sovndal, MD, an emergency physician who practices in the Boulder, CO area told Insider, “but because alcohol skews your judgement, you might feel that when it’s not the case.”
You need a more objective method of gauging your sobriety – and blowing into a breathalyzer is one of the simplest ways to confirm you’re good to drive. A reliable and accurate device will tell you within 30 seconds if your BAC is as low as you feel or whether you should just hang out for another hour. As Sovndal said: “You need to be reasonable and responsible, period.”
Because the most important feature of a breathalyzer is an accurate reading, I tested six devices against various sobriety levels to see how easy each one was to use and how accurate the BAC was. At the end of this guide, I go into more detail on how I tested the devices, as well as what to look for when buying one and FAQs like how you use a breathalyzer and who breathalyzers might not test accurately for.
Here are the 5 best breathalyzers:
- Best breathalyzer overall: BACtrack Trace Professional Breathalyzer
- Best budget breathalyzer: AlcoHAWK Ultra Slim Breathalyzer
- Best high-accuracy breathalyzer: BACtrack S80 Professional Breathalyzer
- Best high-tech breathalyzer: BACtrack Mobile Smartphone Breathalyzer
- Best breathalyzer on-the-go: BACtrack C6 Smartphone Keychain Breathalyzer
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 –
|Test 1 –
|Test 2 –
|Test 2 –
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.
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.
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.
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.
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.”