This indoor air quality monitor (mini CO2 detector) costs under approx. 100–150 PLN (Amazon https://amzn.to/3VRr7jG). Sometimes other variants go for under 100 PLN, like here on AliExpress https://s.click.aliexpress.com/e/_oFuDyuR
I compared it against a professional meter that cost 20–30 times more. Would I recommend it? YES. In some aspects, it’s even better than the expensive ones, though this little gadget isn’t for everyone—you need to know its pros and cons.
Bottom line: it’s the cheapest sensible air quality monitor that measures temperature, humidity, and most importantly, CO2 (carbon dioxide).
How Good Are the Readings?
- Temperature – pretty solid. Whole degrees only (e.g. 21°C instead of 21.4°C), but good enough for home use.
- Humidity – not ideal. In my case, it reads about 4% low, but if you look past that, the accuracy is sufficient for home use.
- CO2 (carbon dioxide) concentration – and here’s the surprise: very respectable, and for this kind of money, actually really good. It handles low CO2 readings well—showing correct values in fresh outdoor air. When levels climb to moderate or high, it tracks accurately too. In theory, it reads slightly high, but well within normal CO2 sensor tolerance (around ±50–70 ppm).
Other Notable Features:
- Extremely compact (W85 x D51 x H17 mm) and light at 75g. Slips right into a pocket, pouch, etc. You can even hang it from a wrist lanyard, bag, etc.
- Because it’s so small, a fold-out kickstand would have been great (it lacks one) so you could comfortably prop it up on a desk and keep an eye on it.
- Battery life is surprisingly long: 14–18 hours. And it charges via USB-C.
- Good display clarity and readability. The only gripe is how it grades CO2 levels around 1,000 ppm, which is already quite high.
The CO2 bar might turn yellow, but it barely moves. The scale just isn’t intuitive. That doesn’t really matter once you know which CO2 values are fine and which are too high. What saves the day is the audible buzzer (can be turned off), which beeps when CO2 exceeds 1,000 ppm—the threshold for comfortable air.
- No extra bells and whistles like history graphs, Wi-Fi, companion apps, etc.—it just toggles between Celsius and Fahrenheit and includes a manual CO2 calibration function that actually works well.
- No pollutant tracking like particulate matter (PM2.5), TVOCs, etc.
Link to the monitor: https://amzn.to/3VRr7jG
Who is this mini CO2 detector for?
- Anyone looking for the cheapest viable CO2 measurement without caring about extra features
- Anyone wanting a portable, or even discreet, way to track CO2 and verify indoor air quality and ventilation
- Anyone who values mobility and wants to monitor air quality and ventilation on the go—in hotel rooms, offices, cars, etc.
Who should skip this mini air quality monitor?
- Anyone who also wants to track pollutants (smog, PM2.5, etc.)
- Anyone who needs data logging (graphs, history) or remote reading via an app or web browser
- Anyone looking for a dedicated desktop air quality monitor—you’re better off spending slightly more on the Dienmern DM125: https://s.click.aliexpress.com/e/_Dl0Atdb
- or the absolute gold standard of indoor air quality monitors, the IQAir AirVisual
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