Oura vs. CIRCUL: Which Is the Best Smart Ring to Detect COVID-19?


If you follow the wearables tech news, you couldn’t have missed American basketball league NBA announcing getting 2,000 Oura rings for the players and staffers to help identify possible contractions of the coronavirus COVID-19.

One cannot help but ask whether smart rings are really up for detecting the coronavirus disease. How can they do it? Which products currently have this capability?

In this post, I will introduce two products that claim capable of detecting COVID-19 – Oura and CIRCUL – and explain how they can do it.

Smart Rings Detecting the Coronavirus COVID-19 – How Did It Start? 

The short history of detecting the symptoms of COVID-19 with a smart ring dates back to early March 2020. Finnish Petri Hollmén, an active sportsman and an avid Oura ring user, saw his readiness score dropped to 54 from his usual 80 to 90, a range considered to be optimal. Apart from having his body temperature slightly above the normal, Hollmén was mostly asymptomatic.

But Hollmén had just returned from traveling across a couple of coronavirus-impacted areas in Central Europe, so he took it upon himself to visit a local hospital and get tested for COVID-19. He turned out positive. This case was the first reported occasion when a smart ring helped a user to detect COVID-19.

RELATED: What Are Smart Rings? How Do They Work?

Can Smart Rings Diagnose Illnesses?

Not yet. Oura, CIRCUL, and other health and wellness smart rings on the market are not classified as medical devices. They cannot diagnose any illness, including COVID-19.

However, health smart rings like Oura and CIRCUL track a wide range of biometric data every day as you wear them. The same data can give you a glance at the state of your health. Sudden deviations or disruptions from your long-term baselines can be an indicator of incubation of an illness. Ideally, with the help of this data, and the algorithms and machine learning developed by the ring-makers, you can foresee an illness such as COVID-19 several days before becoming symptomatic, seek medical advice, get tested earlier, and avoid spreading the virus to others.

Quick Comparison Table

Here’s a quick comparison table of the main features of the Oura and CIRCUL rings. Read forward for detailed information on both health rings.

Oura vs. CIRCUL smart ring comparison table

Oura Ring

Oura Ring is the market-leading health and wellness smart ring that focuses heavily on sleep and activity tracking and self-performance improvement. Oura’s sensors, data analytics, and the mobile app are all perfected towards one goal – to deliver personalized recommendations based on the user’s biometric data so that he/she can optimize life according to his/her unique circadian rhythm.  

Biometric Data in Oura

Oura Ring boasts an advanced sleep monitoring technology, tracking sleep duration and quality on a daily basis and how much time is spent in various sleep stages.  

Oura’s sleep score is calculated based on bedtime, deep sleep, latency, REM sleep, sleep efficiency, time in bed, total sleep time, and wake-up time data. The readiness score, on the other hand, is derived based on body temperature, resting heart rate (HR), heart rate variability (HRV), and respiratory rate. The third score, called the activity score, is based on the following data: activity burn, total burn, activity goal completion, activity score, inactive time, steps, and walking equivalency.

Apart from sleep tracking, the Oura Ring features a range of tracking capabilities for body temperature, pulse amplitude, heart rate, heart rate variation, respiratory rate, and even slight hand and finger movements.

How Oura Detects Symptoms of COVID-19

When the new NBA basketball season kicks off again after the break in the Walt Disney World in Orlando, the players and staffers have the option of wearing the Oura ring to enable an additional safety measure against the spread of COVID-19.

Oura’s algorithm derives the likely symptoms of COVID-19 by combining the following data: heart rate (HR), heart rate variability (HRV), temperature, and respiratory rate. The algorithm calculates a risk score, which indicates a risk of a player having COVID-19 contraction. In case the score is high enough, the player should get tested by the medical professionals.

It takes five days on average for a person to feel any symptoms of the coronavirus disease. During that incubation period, they can spread the virus to others around them. According to Oura, its ring can detect the symptoms typical for illnesses such as COVID-19 (fever, disruption of sleep, tiredness, etc.) several days before the user feels sick. 

So, although Oura cannot diagnose COVID-19, it enables informed testing, which can be an effective and cost-efficient way to slow down the viral spread of COVID-19.

Oura’s Research

Oura is currently investing heavily in research work, partnering with a few universities such as the Universities of San Francisco (UCSF) and San Diego (UCSD) and West Virginia University Rockefeller Neuroscience Institue (WVU-RNI) to find out how its product can be used in identifying various illnesses. The study with UCSF centers on discovering whether the Oura ring can predict illness symptoms. Meanwhile, the national study with RNI is designed to fast-track early detection of the COVID-19 symptoms.


The CIRCUL ring is developed by BodiMetrics, an American health and medical tech specialist company. The Reddot award-winning CIRCUL is a sleep and fitness ring with blood oxygen tracking. In fact, based on the breadth and depth of its spec sheet, the origins of the CIRCUL ring seem to stem from the health/medical wearable technology world. However, it is not cleared as a medical instrument yet.

What Does the CIRCUL Ring Do?

CIRCUL is a highly functional sleep and fitness ring, which also features blood oxygen tracking. You can use CIRCUL for continuous daytime and workout monitoring and overnight sleep tracking for up to 12 hours.

The rich biometric sleep data tracked by CIRCUL includes the blood oxygen level (SpO2), heart rate (HR), oxygen desaturation index (ODI), and the four sleep stages: awake, light sleep, deep sleep, and REM sleep. The daytime monitoring of SpO2 and heart rate are also included, as well as workout monitoring for running, walking, and biking. The data for the workouts and sleep are recorded and can be viewed on the mobile app and easily shared with a trainer, physician, caregiver, or family member.

The CIRCUL ring design features a unique adjustable sizing mechanism, which makes choosing the right size a lot less of an issue. There are only three adjustable sizes available: small, large, and extra-large. A sizing kit is not necessary with CIRCUL, and it can be used on all fingers.

How Does CIRCUL Detect Symptoms of COVID-19?

Whereas Oura combines body temperature, heart rate, heart rate variation, and respiratory rate data for detecting the symptoms of COVID-19, CIRCUL has a different approach. CIRCUL is based on tracking the blood oxygen level.

Why does blood oxygen level matter in COVID-19? When you breathe in air, tiny capillaries in your lungs absorb the oxygen, allowing it to enter your bloodstream. Red blood cells then carry that oxygen to the tissues throughout your body, including your brain and other vital organs. A low oxygen level in your blood could lead to low oxygen in your tissues, and, ultimately, organ failure.

Based on the learnings as of today, the coronavirus primarily attacks via lungs. It affects the lung cells that make surfactant, a substance that helps the air sacs in the lungs stay open between breaths to enable normal lung function. The inflammation developed by COVID-19 causes these air sacs to collapse and disrupt the blood oxygen level. Initially, during the so-called silent hypoxia, patients can still feel fine – i.e., do not feel short of breath. This allows pneumonia to worsen, and, for some patients, it can eventually develop to acute respiratory failure.

A COVID-19-infected person may be dangerously low on oxygen without realizing it. This can be detected by measuring blood oxygen level, and this is how the CIRCUL ring claims to detect COVID-19. The same method is used in pulse oximetry devices (the clip-like device mounted on your finger to measure the blood oxygen saturation in hospitals), which are used in hospitals to detect symptoms of COVID-19, among many other illnesses. 

The FDA has neither reviewed nor cleared the CIRCUL ring for diagnostic use. CIRCUL recommends you speak with your physician about the use of CIRCUL during the pandemic.

You can set up the CIRCUL ring to alert if the blood oxygen level dips below a certain threshold. While this does not qualify as a COVID-19 diagnosis, you can contact your doctor for further medical advice and virus testing. 

Oura or CIRCUL – Which One to Choose?

Despite smart rings cannot directly diagnose illnesses just yet, their data can give you an early indication of illness to enable informed testing – to help you to take better care of yourself and avoid spreading diseases to others around you.

Both Oura and CIRCUL provide viable, yet medically unverified solutions for getting help for tracking the early signs of COVID-19. To make a definitive judgment as to which one of these methods (HRV vs. SPo2) provides a better alternative for detecting COVID-19 still requires more objective medical evidence on how the virus affects our various biometric signals.

That said, both of these products have a lot more to offer when it comes to helping you to live a healthier and more balanced life.

For example, should you want to make the most out of your career, maximize your physical output during exercise, or optimize your daily work-life balance, you probably benefit most from Oura’s vast expertise in how to best align your schedules according to your circadian rhythm. Oura looks good, too. It will keep your fashion-savvy, yet street-wise facade intact no matter where you go, and what you wear with it!

On the other hand, if you want to get an easy-to-use, hassle-free device that fits any finger, and simply provides you with accurate and continuous tracking of the most essential biometric data on a clear mobile app, and allows you to easily share online reports with your family members, trainer, or doctor, you are probably better off with the CIRCUL ring. Thanks to its ingenious adjustable body, sizing is the least of your problems when ordering it!

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