A disposable breathalyzer is a small plastic tube you blow through once and then throw away. Instead of a number on a screen, it shows a color change when the alcohol in your breath reaches the cut-off printed on the label. The appeal is simplicity, with nothing to charge or calibrate. The limit is that one tube answers one narrow question once. This page explains how these tubes work according to the maker's FDA filing, what the cut-off levels mean, and when a low-cost reusable tester is the smarter purchase.
Single-use crystal tubes with a printed cut-off, because there is nothing to charge, maintain or recalibrate, and each guest gets a fresh tube.
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BACtrack C6, a reusable fuel cell keychain unit that shows a reading instead of a color, so repeat checks cost you nothing extra beyond batteries and mouthpieces.
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BACtrack Go, a budget semiconductor keychain tester that replaces a stack of tubes with one device, with clear limits on how precise it can be.
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| Model | Sensor | Stated accuracy | Calibration | Best for |
|---|---|---|---|---|
| Single-use crystal tube | Chemical color change | Qualitative, yes or no at the printed cut-off | None required | One-off checks, events, travel |
| Electronic breath tube system | Single-use tube read by an analyzer | Lot specific, set by the analyzer | Lot-calibrated analyzer | Workplace screening programs |
| BACtrack Go | Semiconductor | Not published by the maker | Every 6 to 12 months, send-in service | Occasional personal checks on a budget |
| BACtrack C6 | Fuel cell | Not published by the maker | Send-in service, interval not published for this model | Repeat personal checks with a number |
| BACtrack Trace Pro | Fuel cell | +/- 0.005 at 0.050% BAC | About yearly, send-in service | Frequent or shared use |
The best documented design comes from an FDA 510(k) summary for a single-use breath alcohol detector. Inside the tube sits a two-part glass vessel holding pale yellow crystals coated with potassium dichromate and sulfuric acid. Alcohol vapor in your breath is oxidized by that coating, and the indicator turns into chromium sulfate, shifting the crystals toward a light aqua, greenish blue color.
The maker sets the amount of indicator chemical in each tube to match one cut-off, so a tube marked 0.04 changes color at or above that level and stays mostly yellow below it. The result is qualitative: you learn whether you are probably above or below one point, not where you sit between zero and that point.
The filing states that no calibration is required. There is no sensor to drift, because the chemistry is used up the moment you blow.
The filing lists four cut-offs printed on the labels: 0.02, 0.04, 0.05 and 0.08 percent breath alcohol. Pick the tube by the question you want answered. A 0.02 tube matches the zero tolerance screening line used for drivers under 21 in many states and the lowest DOT workplace screening point. A 0.04 tube matches the commercial driver threshold. A 0.08 tube matches the per se limit for most adult drivers, and 0.05 matches the Utah limit. Our legal alcohol limit page explains each of those lines.
This is an estimate. It cannot tell you whether you are safe or legal to drive. If you have been drinking, do not drive.
Read the result in good light, following the instructions on the package. A faint or uneven change is the hardest result to judge, and the tube cannot be used again to confirm it. The filing also reports one false positive in 1,200 alcohol-free readings of the 0.04 tester.
Spec source: maker's published specifications
Who it suits: hosts who want something to hand guests, travelers who do not want another gadget, and anyone who expects to check only a few times a year.
What to know: the maker's own filing says the tube is only an indication of the possible presence of alcohol and is not intended to legally determine blood alcohol level or intoxication. You get no number, and an unclear color cannot be retested with the same tube.
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A related design appears on the NHTSA list of screening devices: a single-use breath tube that is read by an electronic analyzer, with each tube matched to the analyzer by lot and unusable after its expiration date. Sections 40.245 and 40.267 of 49 CFR Part 40 set rules for these devices, covering expiration, the lot-calibrated analyzer and reading time. They belong to employer testing programs, so we do not link a retail listing. Employers can start with our guide to dot breath alcohol testing.
Spec source: maker's published specifications
Who it suits: people who keep buying tubes for regular weekend checks and would rather own one small device.
What to know: a semiconductor sensor is less selective than a fuel cell and drifts faster, and the maker publishes no numeric tolerance. Read our bactrack go keychain breathalyzer review for the full spec list.
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Spec source: maker's published specifications
Who it suits: anyone who wants a real reading many times over and likes the idea of a tester small enough for a key ring.
What to know: the upper range stops at 0.300% BAC, and the maker lists it on its send-in calibration service without publishing a model specific interval. See the bactrack c6 review.
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Disposable tubes earn their place at an event where guests should not share a mouthpiece, on trips where a charger is one item too many, and for the person who checks once or twice a year and would never send a reusable unit off for calibration.
Once you test regularly, every tube is a new purchase, while a reusable tester spreads its cost over hundreds of blows and gives you a number you can recheck. Compare the reusable picks on our cheap breathalyzer page or the fuel cell breathalyzer category.
Follow the package instructions, since blowing time and reading time are part of the design. Wait at least 15 minutes after your last drink, meal, cigarette or mouthwash so mouth alcohol does not color the crystals, and keep unused tubes sealed and away from heat. For the reasons behind the wait, see how long to wait before using a breathalyzer.
They are built to change color at one printed cut-off and the maker describes them only as an indication of possible alcohol presence, so treat the result as a rough screen.
No, the chemical reaction uses up the indicator crystals during the first test, so each tube gives exactly one result.
No, the FDA filing for this design states that no calibration is required because the chemistry is consumed in a single use.
Pick the level that matches your question, such as 0.02 for zero tolerance, 0.04 for commercial drivers or 0.08 for the adult per se limit.
No, it is a screening device and cannot tell you that you are safe or legal to drive, so if you have been drinking, do not drive.
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