Wellue O2Ring, a Compact Night Oxymeter Review

Wellue O2Ring, a Compact Night Oxymeter Review

September 17, 2021 10:59 EST • Alexandre Vallières-Lagacé • 8 minute read

Being a Geek often means that you are constantly looking for better numbers. Not only faster CPUs or more memory, but often you also want to track specific metrics about your health. The Apple Watch does many of those automatically, but if you are looking to see the impact of various life events on your health, you often need a more precise and specific product.

I am suffering from sleep apnea and have tried the CPAP machines, however, I was never able to sleep with such a device. The fallback plan was to use a special mouth piece that brings my jaw forward and opens my airways. The only metric I had to go on was that it eliminated my snoring. However, I still wondered if it actually allowed me to get enough oxygen as I had no way to measure this. Until now!

The O2Ring by Wellue is an oximeter outfitted inside a ring shape device that you wear all night and it tracks your blood oxygen levels every second you wear the device.

By using the code “Alexandre” you will get 10% off on the O2Ring!


The unboxing experience is simple and clean. You immediately see the O2Ring that comes as a rounded display set on a rubber ring. The shape reminds me of the 80s “feeling stones” rings that could read your emotions and change colours based on it. It’s about the same size but a bit thicker.

The rubber ring feels very fragile, and after trying to fit it on my thumb, I was barely able to set it there. Tried other fingers like my ring finger and it was not comfortable. It cut the circulation after a few minutes. I was suggested to use the pinky finger as any finger will work fine.

This is much more comfortable and I can wear it all night without discomfort or feeling I will break it by stretching it too much. The size of the device is not large, but sometimes it can get in the way and a few times when resetting my pillow I felt like I almost ripped it out. These times I wished it was more compact!

The display is a nice little display that displays your recorded O2 level in percent as well as your heart pulse rate. Easy to see and not disturbing during the night. You could spot some of the red light leaks around your fingers at times, but it was never enough to wake me or my wife during the night.


  • Transmissive oximetry technology
  • 4 second-recording intervals
  • 4 sessions of 10 hours recording memory, unlimited datasets in app
  • lots of customization options
  • report generation, CSV, PDF and binary exports
  • compatible with Apple Health
  • FDA listed


I’ve tried it for many nights and I also tried to use it when I had a different routine to see how it would affect my oxygen level during the night. I’ve always worn my mouth piece for sleep apnea so that I could finally know for sure if the mouth piece worked or not.

First, let’s get this out of the way.

This is not a diagnostic tool as with all consumer oximeter, there is a ±4% accuracy buffer, so this means that if the device reports 90% you could be anywhere between 86% and 94%. You can use this information to start discussing your situation with healthcare professionals but this data should not be used as final diagnostic data to define a treatment or medication.

The device is FDA listed which means that it’s known by the FDA but not that it was tested or approved by the FDA. The manufacturer is registered and so is the device. Here’s the FDA listing for you to review. The Class 2 means that devices in that category “require some regulatory control of safety and effectiveness.” This basically means that it’s a good tool, but not a medical approved diagnostic tool.

Battery Life

I put it on when I go to sleep and take it off when I get out of bed. I tried to capture more than one night on a single charge, but I was not able to complete the second night in full. They advertise up to 16h on a full charge, but I was able to get exactly 15h of recording over two nights.

Even if it dies during the night, it still keeps the partial night data and you lose nothing of what was recorded.

Data Syncing

In the morning, I would put it back on and open the iOS app to sync the data. It takes a reasonable amount of time to sync via Bluetooth all the data. About 12-15 seconds for a full night. It also syncs very short periods when I just put it on to sync the data or see my current heart rate. I usually delete those and only keep full night data sets.

O2Ring Mobile App

They advertise 4 groups of 10 hours, so about 40 hours of recording on the device itself, but I never reached that. I usually sync it after one or two nights. And unlimited storage inside the mobile application.

Once synced, you can see the reports and lots of interesting details like the total time < 90%, the drops over 4% and the number of drops per recording session. You even have an O2 Score that can be an easy metric to track and see how good you were oxygenated during the night. The average heart rate will also help you to see if you are putting unnecessary strain on your body because of a sleep condition like sleep apnea.

I love that you can add notes to your recording session, you can use this to note things like at what time you got to sleep, or if you have been drinking alcohol or coffee the night prior. This is helpful to track as you will forget.

Warning and Alerts

There is a feature where you can set a limit and if it is reached or passed the O2Ring will alert you and note it in the data set. This is useful if you want to be woken up by the vibration if you enter a dangerous zone. Also, if you keep the app opened, the app can also alert you audibly.

Example of a bad night

Personally, I never reached the default threshold they set at the factory. Thankfully, this means even at night where I get many O2 drops, it never drops to dangerous levels. Most probably because of my mouth piece, though. I did not want to start snoring again so I did not stop wearing it as it will mess with my wife’s sleep.


The reports can be exported as PDF and shared with your healthcare specialist, but at the same time it can sync your data to Apple Health. I have enabled this as I also track my blood pressure with a non-smart device where I enter my systolic, diastolic pressure and heart rate using a custom iOS Shortcut I wrote to quickly enter the data in Apple Health.

O2Ring Mobile App Report Exporting

This way I have my night oxygen level, night heart rate, resting heart rate when I take my blood pressure and my blood pressure, all in the same app. I would also recommend to look at the Heart Report app on iOS, it has very customizable report generation that can also be shared with your doctor. You can choose what metric to include to make them more useful.


After testing the O2Ring for many, many nights I must say that I found the experience very good! It’s not one of the most expensive ring-type devices, and it does not all the things, but it does one thing and one thing well. It’s tracking is efficient and it is very simple to operate. I kind of wish it was slimmer not to get caught in my pillow or sheets while I sleep, though. And it’s 15-hour battery life is not enough as often, I would set it and did not realize it was not fully charged and only captured 3 or 4 hours of data.

If you are looking for more insights into your blood oxygen level, the O2Ring is a great device to do so. It’s reporting is quite good, and adding notes can help you see what you change in your routine and how it affects your sleep quality. For me it was most of all a way to see if my mouth piece was actually working for my sleep apnea and I’m happy to report it does work as on regular nights, my O2 level does not drop significantly.

There are way to make this little device better, though! First of all, ditch the MicroUSB port for a USB-C port. Make it slimmer so it’s more of a profile design, it will probably be less in the way of sheets and pillows. And make it so that the hardware is better optimized for longer battery life! 15 hours is not enough, try to aim for at least 24h which would be about 3 nights of sleep.

Review Summary

O2Ring (model PO2)Shenzhen Viatom Technology Co. Ltd
O2Ring (model PO2)

A small device named the O2Ring by Wellue, is shaped like a ring that tracks your blood oxygen levels through the night and generates reports, all this wirelessly.

Wellue O2Ring
With 10% off with code 'Alexandre'

The Good Stuff
  • Easy to read screen
  • Can fit many sizes of fingers
  • Simple to use
The Bad Stuff
  • Fragile feeling rubber ring
  • Some red light leak
  • Battery life is short for night wearing
The Ratings
Overall: 83%
Disclaimers: This product or service was provided by the company or partner for the purpose of this review.
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