Hello Mypromille Users,

Until now, Mypromille has worked one way: you log what you drink, and the app estimates your blood alcohol content from it. That estimate is good — it accounts for your weight, your sex, the strength and size of every drink, and how long ago you had it — but it is still a calculation based on what you told it.

Today we’re adding the other half. Mypromille can now connect to a Bluetooth breathalyzer and show you a real, measured reading.

How it works:

Tap Measure on the main screen, right under your current level, and the app opens the Breathalyzer screen and starts looking for your device.

  1. Scan: The app scans for nearby breathalyzers over Bluetooth. Wake the device if nothing shows up straight away.
  2. Connect: Your device appears by name. Tap Connect, and it stays paired until you tap Disconnect.
  3. Warm up: The sensor needs a few seconds before it can read anything. The app counts down and tells you plainly: do not blow yet.
  4. Blow: When the status turns to ready to blow, blow steadily while the countdown runs.
  5. Result: The app analyses the sample and shows your measured level in ‰ and in mg/L.
Pairing a breathalyzer and taking a measurement, start to finish. The device’s Bluetooth identifier is blurred out.

Why measure at all?

An estimate and a measurement answer slightly different questions, and it is useful to have both.

  • The estimate looks forward. It knows what you drank and when, so it can draw the curve — when you peaked, and roughly when you will be back down. A breathalyzer cannot tell you that.
  • The measurement looks at right now. It does not care what you remembered to log. If you forgot a drink, poured a heavy one, or your body simply is not behaving like the average the formula assumes, the reading will say so.

Seeing the two side by side is the point. When they agree, your logging is honest and the curve ahead of you is trustworthy. When they disagree, that gap is worth paying attention to.

A word on reading the result:

Breath testing is sensitive to how and when you blow. Alcohol lingering in your mouth from a recent drink, a mouthwash, or a burp will read high and has nothing to do with what is in your blood — so wait a good fifteen to twenty minutes after your last sip before testing, and take a second reading if one looks off.

And the obvious point, which we will keep making: no reading from any app or any device makes it safe to drive. Accuracy varies between devices, alcohol is still being absorbed for a while after you stop drinking, and the only number that counts legally is the one taken by the police. Use this to understand your own drinking, not to talk yourself into the car.

Getting started:

You will need a Bluetooth breathalyzer of your own — Mypromille talks to the device, it does not replace it. The one in the video above is a BACtrack C6:

Make sure Bluetooth is on, the device is awake, and you have granted Mypromille permission to use it, then tap Measure and hit Scan.

Don’t see the Measure button yet?

We are rolling this feature out gradually rather than switching it on for everyone at once, so it may take a little while before it reaches your app. Nothing is wrong on your end and there is nothing you need to do — keep the app updated, and the option will show up on your main screen in due course.

We would genuinely like to hear which devices you are using and how the readings line up with the estimate. That feedback is what tells us which hardware to support next.

Explore More:

Stay aware, stay in control,

The Mypromille Team