Personal alcohol breath testers - accurate?

Hi all,

There have been occasions where I’ve had a few drinks and later driven home, thinking I’m under the limit (I use the one drink an hour rule). But I’m always left wondering - am I REALLY under the limit, or is it borderline, or what?

Occasionally I see adverts for personal breath testing devices.

Are these doodads accurate (yes, I know, standard disclaimers notwithstanding)? If I blow a 0.04 in one of these things, can I be reasonably certain I’m under the limit (0.05 here in QLD, Australia)?


I have not tried that specific model but I have blown a .02 piss drunk on a hand held breathilizer. I figure that was at least .10 below what I should have been blowing.

No, you can’t. In fact, the manuals that come with these things generally have some sort of disclaimer to this effect. Additionally, even if the reading is accurate, other factors come into play, such as the speed of consumption and time. Even if you’re reading below the limit at the time you leave, you could very well be over by the time the police check you. The best rule, as always, is not to drive if you’ve been drinking at all. YMMV.

I too blew like a .05 on one of those when I knew I was drunk. And if I knew I was drunk, that means I was well past the legal limit. But this was -the- cheapest one you could buy, so it’s possible that the better quality ones are more accurate. You could have a fun drunken experiment night with your friends. Do the calculations to find out how much alcohol the average person would have in the blood after consuming x beers, rate how drunk you feel, then use one of those personal breathalyzers. A really good excuse to get drunk and learn at the same time.

On a slightly different note, what about the breathalyzers that you see from time to time in bars? I’ve never seen these in the states, but when I was in Germany, you’d sometimes see coin-operated breath analyzers posted near the restrooms. Never tried one, but I’d suspect they’d be more accurate than the little handheld cheapie ones.

And yeah, typical disclaimer. Breath analysis should only be performed by trained professionals.

Thanks guys! That confirms what I had suspected. It’s all academic anyway, since I don’t drink anymore.

I’ve seen those coin-operated ones as well.

How do these things work, anyway?