SwitchBot Room Thermometer Hygrometer Indoor, Bluetooth Digital Temperature Monitor with Free Data Storage, Dewpoint/VPD/Absolute Humidity, Hygrom...

Very accurate and calibrated. They also fit perfect inside Bell wide mouth leak-proof lids. I use a name tag magnet, tape magnet to outside of lids and then stick metal strip to back of Switchbot. Holds perfect! Great for curing cannabis in Mason jars. Put app on phone and you can check humidity and temp. without openings jars. No more squashed buds!!!

I really love my switchbot products. The first time I bought they looked a bit expensive, but the value for your money is far beyond. You'll need a switchbot hub to see the historical data, over day, night, months. I think the accuracy is very well. Battery life lasts long, I bought my first thermometer in september 2022 and today (may 2024) it has three of four bars.

Ordered four, but one had a bad screen. The manufacturer did end up sending a replacement, but it took a few painful exchanges because half of their emails were not making it to my account for some reason. The one with the bad screen still seems to work correctly, so it might still be useful in an inaccessible place that I will only read remotely. The meters seem accurate and precise, at least within human comfort levels. I tested a few meters and they were almost always within +/- 0.2 c and +/-1% rh to each other and seemed to closely match the official weather conditions when tested outside. However, the precision decreased at temperatures > 40 c outside when in full sunlight or in the attic. The difference between them increased to about +/- 2.0 c and +/- 2% rh. For my purposes, those extremes are not too important as I'll be using them indoors. The app is kind of worthless. It's huge (500MB!) and takes repeated attempts to download new data. I suspect the optional hub would do a better job, but I want to add these to my existing eclectic ecosystem controlled by Home Assistant. That's where these seem to shine: the manufacturer seems to have good APIs you can use to roll your own custom solutions for remote sensing. So as a remote data logger, they seem to be a good deal, especially if you can get them on sale or with a coupon that brings the price down to about $8 per unit or less.

With this latest 4-pak, I now have 12 monitoring temperature and humidity at various locations around the house. Setup was fast and easy once you have the app and an account created. You remove the display protective plastic, open the battery cover, install batteries in the indicated directions, replace cover, press button to select between F & C temperature display, press the + in the upper right corner of the apps home screen, tap the meter after it has been detected, then follow on screen directions to complete. For iOS devices, having the mini-hub is not required as long as you are in Bluetooth range. Otherwise, plan on one or more hubs depending on how widespread your installation is. (Using hubs allows data to be uploaded to the cloud. Each hub also has IR remote control capabilities for devices in its line of sight.) Because I just want consistency between meters, I didnt do an exact calibration. Instead, I just placed them all together in a closed box which I placed in a dead air area for 24 hours. I then selected the temperature and humidity that most agreed upon (mathematical mode) and adjusted the others using calibration to match. Tips: If you have multiple new meters, only power them up 1 at a time when adding them. Also, since there are no serial numbers or Bluetooth MACs printed on these, marking devices will help your sanity. I just used a pencil and wrote the location on the battery cover. Eventually, I may make labels and add them inside the battery compartment. If using the stick-on metal plates to magnetically hang your meter, clean the area and allow it to dry before sticking the tape to the mounting point. Consider replacing the 2 included AAA batteries with your favorite high quality name brand. Set up the rooms or locations in the app prior to adding the meter to speed the process. Also, the room selection appears at the bottom of the screen so you need to hit Done after entering the name. Issues: If I manually tried activating Cloud Services and selecting a hub, it failed to detect the hub on the first attempt but was successful on the second. If I waited until it prompted me, it succeeded the first time. Even though the temperature calibration shows that you can adjust by 0.1F, it varies by about 0.2, indicating its actually adjusting by 0.1C.

I have been using these devices for the past week and here is my take: As a sensor, it does exactly what it says, very accurately. Setup is relatively easy, if you have a hub close at hand. The requirement for a hub itself can be a negative for some, but in all honesty, it doesn't matter much if you don't need to sync the values or connect to cloud services. If you are a tinkerer and use HomeAssistant, you won't need the hub, you can use HomeAssistant's built-in integration to incorporate these devices via Bluetooth into your home automation ecosystem. The major downside for me is that the connectivity technology is built on Bluetooth, and not WiFi. This means that the devices have very limited range when it comes to finding the hub. One of the four in the box can't find the hub for me, due to placement requirements. Once you get past that, though, setup is easy and usage even easier. The provided magnetic tape can be used to install this almost anywhere non-invasively. You can also use the provided stand to keep it sitting on a surface, tilting slightly upwards, which is nice. The display could use a little higher contrast, as it is hard to read in extreme lights (either too dark or too bright). Since the tech used to connect these to the hub is Bluetooth, your out-of-range devices will not be able to find the hub, and as such you can't use cloud services (Alexa, Google Assistant, etc. integration) with it. That's why I'm giving this a 3-star review and not a 5-star. I am not giving it 4, because the connectivity detracts from the "smart"ness of the device, and I wouldn't recommend this to someone who was going to deploy this in a moderately large environment.