People who search for a breathalyzer for a car usually mean one of two very different things. One is a personal tester that lives on your key ring or in your bag, so you can check yourself after a night out and plan a ride home. The other is an ignition interlock device, a unit wired into the vehicle that a court or licensing agency requires after an impaired driving offense. This page separates the two, compares personal testers that suit drivers using their makers' published specifications, and points you to our interlock guides if that is the device you need.
BACtrack C6, a BluFire fuel cell keychain tester that works with its own screen or through the app, so it stays with the keys rather than in a hot or frozen car.
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BACtrack Mobile, a fuel cell unit with a breath pump and a published tolerance of +/- 0.005 at 0.050% BAC that shows results and a ZeroLine estimate in the app.
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BACtrack Go, a semiconductor keychain unit for occasional checks, with no published accuracy figure.
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| Model | Sensor | Stated accuracy | Calibration | Best for |
|---|---|---|---|---|
| BACtrack C6 | Fuel cell | Not published by the maker | Send-in service, interval not published for this model | Keychain carry with app option |
| BACtrack Mobile | Xtend fuel cell with pump | +/- 0.005 at 0.050% BAC | Every 6 to 12 months, send-in service | Phone users who want a history |
| BACtrack Go | Semiconductor | Not published by the maker | Every 6 to 12 months, send-in service | Occasional budget checks |
| BACtrack Trace Pro | Xtend fuel cell | +/- 0.005 at 0.050% BAC | Annual recommended, send-in service | Households that want a pocket handheld |
A personal breathalyzer is a screening device you buy and own. It estimates your breath alcohol and nothing more: it does not connect to the vehicle, does not stop the engine and is not accepted as evidence. Its value is information, for example showing that alcohol is still in your system hours after you expected it to be gone.
An ignition interlock device is installed in the vehicle by an approved provider, usually as a condition set by a court or the state licensing agency, and the vehicle will not start until the driver passes a breath test. Interlocks also ask for retests while driving and keep records reviewed at service visits. A personal tester cannot satisfy an interlock order. Our guides explain the ignition interlock device program and ignition interlock device cost. Interlock service is a separate business, which BACtrack, for example, runs as BACtrack Drive.
The best time to use a personal breathalyzer is before you need a decision, not at the car door. If you plan to drink, plan the ride home first and treat the tester as a way to learn how your body handles alcohol over time.
This is an estimate. It cannot tell you whether you are safe or legal to drive. If you have been drinking, do not drive.
A low reading right after your last drink can be misleading, because alcohol keeps moving from the stomach into the blood for some time. That is why makers ask you to wait before blowing. The BACtrack manuals ask for 20 minutes after eating, drinking or smoking, and many other makers ask for at least 15. Our article on how long to wait before using a breathalyzer covers the reasons, and the legal alcohol limit page explains the numbers drivers are held to, including the stricter limits for commercial drivers and anyone under 21.
Leaving a tester in the car is convenient, but a parked cabin can get far hotter or colder than a sensor is designed for. The BACtrack Go manual lists an operating range of 50 to 104 F and the BACtrack Mobile user guide 32 to 96.8 F. A summer afternoon or winter night can push a cabin outside both, and the other models here publish no operating range at all.
Our calibration guide counts a long stay in a hot car among the signs a unit may need a check. Keep the tester on your keys or in a bag that comes inside with you, which is why keychain and phone-based units suit drivers.
Spec source: maker's published specifications
Who it suits: drivers who want a fuel cell tester that is always with their keys.
What to know: no numeric accuracy is published, and the range stops at 0.300% BAC. See the bactrack c6 review.
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Spec source: maker's published specifications
Who it suits: drivers who already rely on their phone and want a record of results plus an estimate of when they will read zero.
What to know: there is no screen on the unit, and the ZeroLine figure is an estimate, not a clearance to drive. App privacy terms are not stated on the product page or in the user guide. Read the bactrack mobile pro review.
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Spec source: maker's published specifications
Who it suits: drivers who want a small, low-cost device for a few checks a month.
What to know: there is no published accuracy, the manual says not to use the result to decide whether to drive, and the battery covers fewer tests than the fuel cell keychains. See the bactrack go keychain breathalyzer review.
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Spec source: maker's published specifications
Who it suits: families with teen drivers who want one accurate handheld that stays in the house.
What to know: it is larger than a keychain unit and has no app. Parents can read our article on a breathalyzer for teen drivers and the bactrack trace professional breathalyzer review.
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Start with where the device will live. If it rides on your keys, a keychain fuel cell like the C6 is the natural fit. If you always carry your phone and want a log, the Mobile does that job. If the tester stays at home for the whole family, a handheld such as the Trace Pro gives a published tolerance and a longer battery life. Then look at the sensor: a fuel cell is alcohol specific and steadier, while a semiconductor unit is cheaper and rougher. Finally, check the calibration path, because a tester that is never recalibrated slowly drifts. Our personal breathalyzer and keychain breathalyzer categories go deeper on each format.
It is better to keep it on your keys or in a bag, because car cabins often go outside the operating temperatures makers publish.
No, a court or licensing order for an interlock can only be met by a device installed by an approved provider.
No, it gives an estimate that cannot tell you whether you are safe or legal to drive, so if you have been drinking, do not drive.
A fuel cell keychain or phone-based unit suits most drivers because it stays with you and is alcohol specific.
Wait at least 15 minutes after your last drink, food, smoke or mouthwash, and 20 minutes if your BACtrack manual asks for it.
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