$189.00 Price may change
15 videosWalter H. Williams III
Been using this sensor in a commercial setting for commissioning HVAC systems. Here I can compare it with professional tools the TAB professionals are using and it's very close for a quarter of the price. Awesome!
RR
We have been using this carbon dioxide (CO₂) monitor for the past 18 months to check carbon dioxide levels in our home and work areas. CO₂ levels are a key measurement to assess the quality of indoor air and ventilation, which are important for minimizing the risk of virus transmission.
One of the main reasons we bought it was to monitor how good the ventilation is in our indoor rooms.
For example, in our home office, when the readings went up to 1,000+ ppm (parts per million), we noticed that our thinking slowed and we felt more sluggish. Decisions become more difficult to make.
Apparently, our experiences match scientific studies that have proven that high levels of carbon dioxide can impair cognitive function and make it harder to think and be productive when CO₂ levels hit 1000 ppm and above.
Thanks to this air quality monitor, we also noticed that if a second person enters a room, the CO₂ levels can increase quite rapidly just from our breathing. The CO₂ readings can sometimes double. We open a window to bring it back down to a good range.
This monitor is small enough so that you can hold it in your palm and move it around easily. It looks both sleek and functional.
Big bonus: it also provides temperature and humidity readings, and you can select either Fahrenheit or Celsius. To have all these readings all on one small device is very handy.
It runs on two AA alkaline batteries, which are included. There is a helpful bar showing how much battery life is left.
We have had our unit for 18 months, and after continuous use, we have not had to replace the batteries.
The e-ink display digits are bright, easy to read, and large (roughly half an inch tall).
The large digits and color bar allow you to quickly glance at the device from a distance and assess whether to take action to reduce CO₂ levels.
There is an air quality bar that has three colors: green, yellow, and red. Each color corresponds to a different CO₂ level: green for normal (good), yellow for elevated (average), and red for high CO₂ levels (unhealthy).
The second reason we purchased this monitor is to get an idea of how high the risk of respiratory virus exposure is. Higher CO₂ levels indicate poor ventilation, which can lead to higher airborne virus concentration. Scientists have found that people in a room with higher CO₂ levels are at a higher risk of virus infection than people in an identical room with lower CO₂ levels.
Therefore, knowing when the CO₂ levels are high allows you to know when to reduce risk by opening windows to allow fresh air in, wearing a high-quality respirator mask, and/or reducing the time spent in that space.
One feature we like is that you can use it with or without the app. So there is no pressure to use the app. Our only wish is that it came with a protective cover.
In sum, this is a high-quality, reliable, and easy-to-use CO₂ monitor that allows you to continually assess air quality and ventilation. This was quite an investment, but well worth it. Highly recommended.
Sandy Perez
It's a very nice little device. I tested it against 2 other devices but they give wildly different results, if they were programmed to display random numbers I think the results would be the same. And that's the problem, how do we know which one gives an accurate result? We don't.
I know the aranet4 was the least accurate for the temperature in my tests as I had other thermometers in the rooms. Does it mean it's not accurate for the CO2? No.
I'll return all 3 and I guess I'll just open my windows.
円相
Not the cheapest for sure, but like many things, you tend to get what you pay for.
In this case, for me, after over almost 3 years of continuous use a device that's:
- reliable, accurate (tested against calibrated devices) and convenient
- tested in NE USA and SE Asia, and even used carried in a bag through subway systems
- battery lasted about 2 years
- excellent reporting/charting app (7 days worth of readings - exportable as .csv/.xlsx) and bluetooth comms, flawless device firmware updating
Easily worth the money over time.
Power Squirrel
Screen stopped updating after 1.5 years of use. On a positive note, the unit still seems to be reporting the correct data in the app.
D.
I've had it for a little over a year and a half. Really love it. From just checking the CO2 in my bedroom, to checking the CO2 in my greenhouse, it's a really practical gadget for anyone living/working in enclosed spaces.
App is great, and viewing historical data is a breeze. Just wish it had wifi functionality for remote viewing when not at home, but I'm sure it would add to the cost of the device, and it would probably drain the better a lot quicker.
I emailed Aranet about it, to which they simply replied, "our sensor is more accurate." So, I guess I just have to average out the difference since I trust both Aranet and the competition. The truth lies somewhere in between lol
A Person
Nice to know (or even as a reminder when you walk by) when I should open my windows or turn on our vents. Easy to see how over night the number goes up with lots of people breathing in the house (and dogs). Then in the morning using vents or opening windows it drops back to a good level.
Would be great in places with fires or big cities for sure, still useful in the burbs though.
PK
Good device. Helping keep your place air condition nice and healthy. Recommend
SML
This Aranet 4 is a useful and dependable tool for measuring CO2, humidity and temperature in a room. It works well, and the temperature is consistent with my thermostat. It is easy to carry when I travel, attend meetings, and even when I am driving. It works through netting. I recommend it. Fresh air is important!
Stu
Initially bought to evaluate if we wanted to switch our range from gas to induction. But then started measuring home office (surprisingly bad), kids room, flights (yikes!), etc.
The refresh rate is maddeningly slow, but I guess that’s the price we pay for long battery life.
It’s a winner. Wish it measured CO too.
Austin Edens
The screen quit working on this expensive item after 5 months and no one will communicate with me. Don’t buy.
Ryan M. Johnson
The screen froze one day and they didn’t respond to a support inquiry.
Richard W
This is a fantastic sensor. The e-ink screen is so nifty, and it is the perfect little size.
You don't need an app to use this sensor! But if you want to use the app, it is free and there is no subscription. Really wonderful in today's world. I'll for sure be buying more sensors from this brand in the future!
Absolutely worth the price.
Dmitry
Outstanding battery life, great overall build quality, easy and intuitive app UI.
Mechanical Engineer
Excellent product, except for an overlooked design flaw.
I noticed that the CO2 reading were being affected by indoor particle pollution. When I researched this I found that is exactly the case NDIR sensors are affected by particles floating in the air, so much so that I had to place HEPA filter discs over the vent openings, see picture. Now the CO2 reading is accurate.
If you want accurate readings you MUST cover the intake vents with HEPA filters.
I used Zonon Synthetic Filter Paper Stickers 20 mm Filter Patch Sticker 0.25 µm Filter Paper.
I tested the zero point by placing the Aranet4 inside an air tight bag with 4A molecular sieve (adsorbs CO2) and watched the readings go to zero.
NDIR sensors are also greatly affected by humidity, see graph. The humidity has an overwhelming affect, but it is nearly impossible to filter out water vapor. H2O is a very small molecule and desiccants (molecular sieve and silica gel) also adsorb CO2.
CHENGYU YOU
It's one of the best CO2 monitors I've ever bought. Accurate and long battery life. I love this e-Ink screen!
Mary
I love everything about this. Once the reading goes above 1000ppm I open the windows and it decreases. Still want to bring this into stores and restaurants - love that it’s portable.
D. A. H.
Will this thing is a wake up call. Outdoor air is in the 400s and inside is mid 1500s. I’m keeping this for the bedroom or office. But I’m buying a more capable, affordable, open source AirGradient for my next two monitors. I can’t recommend AirMatters; they don’t seem to have the same level of commitment to python/accessibility as Aranet.
I can definitely recommend this product.
Update: I got the Python using the Aranet4-Python library. Finding the MAC address was a bit tricky. So glad this feature is supported.
Alex P
Got this unit to measure CO2 in my home office, as I've been spending a lot of time in there. Was getting into the yellow zone during the day, so I have set up some fans, and also open the windows on occasion. Now, I have no excuses for loss of productivity.
The only tricky part is to switch the Centigrade to Fahrenheit - small switch under battery. Then also in the app, under the hamburger menu.
Highly recommended if you want to check CO2 levels.
Also tracks temperature, humidity, and air pressure. If that matters to you.
C N
Easy to see why there are so many fans of this device.
Now I have data matching up to the times I have trouble sleeping or concentrating!
Thanks to its readings and the app, we are getting our gas-based heating system down in the basement checked for leakage problems, and stay aware of circulating fresh air inside.
Since the Aranet4 is fragile & slippery to hold, I use its box as a case.
Small, light, useful in these troubled times.
Alexander O.
I've used this for the last 6 months in public places and particularly while traveling. The CO2 monitor shows clearly where the air is of good quality vs where it isn't. The pictures show two flights and one train ride as examples.
O
Very disappointing stopped working after a few weeks
M. Smith
For those of you who are looking for a suitable protective soft case for the Aranet4, I've found that the "Casematix Crypto Wallet Case Compatible with Ledger Nano S, Ledger X, Trezor Model T" etc is the perfect size for the Aranet4 with batteries installed. This isn't a good case to use for airflow in, but if you want to travel with your Aranet4 without damaging it, the case is perfect.
Lucas Nicodemus
I've owned several CO2 sensors. In particular, I've had 2 Awair Glow units, 1 first-generation Awair unit, 1 second-generation Awair unit, and a TIM10 CO2 sensor. Of these sensors, the TIM10 is my "gold standard" sensor, but it has the very, very annoying property of requiring AC power. Aranet4 promised to be a battery-powered CO2 sensor that could output data to an app. It delivers, but it requires calibration out-of-the-box, in my opinion.
Measured against known good sensors (particularly my TIM10), my Aranet4 sensor read about 75ppm higher than the environmental level out-of-the-box. The app warns you that performing calibration will permanently erase the factory calibration data, which is somewhat scary, but I did it anyway. In order to validate that the calibration was successful, I had my trusted TIM10 sensor outdoors, connected to AC power, out of the sun, with the Aranet4 directly next to it, on a substantially windy day with extremely good air quality (as measured by PM2.5 and PM10 presence from AirNow and Purple Air). The floor, outdoors, in this configuration, as read by the TIM10 unit, was 380ppm of CO2. Before calibration, in the same environment, Aranet4 reported 480ppm. After calibration, Aranet4 reported within 15ppm of TIM10, which I considered a success, particularly given the rarity of having such a low reading. All of the Awair units bottom out at 400ppm.
Following calibration, for the last few weeks, I've kept an eye on Aranet4 and TIM10 when they've been in the same room. There's approximately a 10-15ppm disagreement between TIM10 and Aranet4, which I consider a very acceptable deviation given that Aranet4 is battery powered, and TIM10 is AC powered.
On the app side, Aranet4 provides a serviceable iOS app. The iOS app itself is perfunctory. It provides graphing, exporting data (as csv, including CO2, pressure, humidity, temperature, and date of sample), and basic reporting features. It doesn't support dark mode, though, as an example of its perfunctory nature. The app developers didn't consider the performance impacts that storing all of the data would have on the graphing component, though, so the app gets laggier the more data the sensor measures. You're also only going to get a week of data for historical measurement.
Other details are worth mentioning beyond the sensor accuracy and app integration, though. E-ink, as a display type, is just awesome. It looks very nice, aesthetically. Each refresh blanks the screen temporarily, though. Keep this in mind, if you decrease the measurement interval (you can measure as frequently as once per minute). Also, there's no backlight, which is why the battery life is good, but keep this in mind too, if you want to see it in the dark.
I've taken this sensor on an airplane, and it works great there too. It's just an incredible sensor to have -- you can pocket it or bring it somewhere in a backpack and still have CO2 measurements, where most sensors can't go. For travel, or just in general, it's a great device to have. After calibration, it measures very accurately, and I'm happy with my purchase all around. However, I'd say calibration is mandatory.
I've included a screenshot of a graph made from the CSV, as well as the CSV data from the unit itself.
Pipat S.
The item is easy to use and I like its design a lot. Very helpful and it keeps me aware of my environment.
DonS
I’m cabin crew and I take this sensor with me on my trips.
I’ve learned to see patterns with each flight — a high buildup of CO₂ during boarding of 2,000-3,500ppm. This quickly decreases after pushback but will increase again if deicing is necessary since the air is turned off. During cruise it levels off to around 1,400-1,600ppm when the air is finally being recycled through HEPA filters every 2-3 minutes and the humidity drops below 15%. Holding out for an occupied gate causes the readings to tick back up toward 2,000ppm after 15-25 minutes. I’m attaching a sample reading from a recent flight.
I also appreciate seeing the air quality of each airport — they’re actually pretty good!
I’ve been paranoid about my hotel air quality since most windows are sealed shut, but so far I haven’t had CO₂ levels above 1,000ppm unless I’m engaged in the occasional overnight activities. Usually I get into my hotel room with an initial ready of 550-650ppm and leave the next morning with it less than 800ppm.
Isabelle, Ontario
Open your windows just just 4 minutes and CO2 level drops 40% ! Open your windows, ventilate, and measure ! Aranet4 is great and is portable.
Thanapon
Very easy to use. I recommend all cafe and restaurants to get one.
Kevin C.
I bought two and they differ by 6-8% whether they're indoors or out. They're useful though. I'm more careful about keeping windows open when possible, and I've noticed I feel better when it stays below 600.
Dani
Great little air quality monitor! The small size and clean design is perfect for our modern household. The display is easy to read from across the room. Using the Android app we set our C02 threshold at 1100 ppm, Aranet4 beeps an alarm when it's time to ventilate the room.
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