Let’s Discuss Oura Ring vs Circular Ring Slim, Shall We?

I have seen the Oura ring everywhere. It’s popular on social media platforms, people make long, detailed videos marveling at its beauty, so many celebrities have been snapped wearing it (Hi Kim!), and whatnot. And, well, I am in on the hype, too.

But, you know, apart from Oura, the smart ring market also has some other pretty worthy players, such as the Circular Ring Slim. So now the question becomes if these contenders are as wonderful as the Oura ring or not. If you think of it, that’s a pretty interesting question.

Therefore, I have taken it upon myself to investigate the matter, i.e., compare these other rings with the Oura. In this particular article, I have shared how the Oura Ring compares to the Circular ring. My final verdict is given at the bottom, so if you want to make your acquaintance with the winner, keep scrolling!

Design & Colors

Oura comes in two different styles and several colors, so there were plenty of options for me to choose from. I got my Oura ring in the Heritage variant and black color since that appealed to me the best.

On the other hand, the Circular offered me no such choices. As of now, the Slim Ring is only available in a matte black finish, and so that is what I got.

You might think that, given that both of the rings I was comparing were nearly the same color, it’d be difficult for me to tell them apart. But it was actually pretty easy.

My Oura wasn’t completely circular, whereas the Slim Ring was—at least on the outside. The palm-facing inside part of the Circular Ring is flat and has two charging rails attached to it. On either side of the charging rails are sensors that do all the work.

The Heritage version of the Oura ring comes with a flat top. But while my Oura is flat on the top and not completely circular on the outside, it is so on the inside.

Another distinguishing feature between the two rings is that Ring Slim has a small white circle at the top. While the circle is placed there for a reason— it’s the Circular logo that also acts as a reactive button, I still think it does nothing to enhance the ring’s appearance.

Because you know what? While both of the rings may be of the same color and look identical, up close, the Oura Ring looks way better than the Circular Slim. Oura is shiny and classy; it has a premium feel to it. Whereas the Circular ring has a plastic feel to it. I am not kidding here since it feels roughly the same as Oura’s sizing kit rings feel.

Furthermore, Oura does manage to complement my outfits, whereas Slim Ring somehow stands out. I blame it on the small, rather unnecessary white circle logo and plastic feel.

So, obviously, I like Oura because of all the different color and finish options it provides me with. While black is always my top choice, if I ever get bored with it in the future, I have the option to choose other colors like silver, stealth, gold, rose gold, etc. The same can’t be said for Circular.

Materials, Comfort & Durability

Do you know why the Oura Ring and Circular Ring look so different up close? No, it’s not just about the circle logo-cum-button thing the latter has. It’s also about the materials they are made up of. While Oura is made up of durable titanium, the Slim Ring has been crafted from aluminum and carbon fiber.

Plus, I don’t think the Slim Ring is interested in looking like Oura anyway. Maybe Ultrahuman AIR is Slim Ring’s inspiration. With a measuring thickness of 2.45mm and weighing just 2.4 grams, Ultrahuman AIR was considered to be the thinnest and slimmest ring on the market, but then came the Slim Ring to steal its glory. True to its name, the Slim Ring weighs just 2 grams and is only 2.2 mm thick.

Needless to say, the Circular Ring felt thinner and lighter on my finger than the Oura. The Oura, with its around 5 grams of weight and 2.55mm thickness, felt bulkier. It has never felt so in comparison to other rings, but then I never had compared it with Circular Slim before.

However, surprisingly, Circular Slim (8.8mm) was wider than Oura (7.9mm), which made it more noticeable. Slim may be thin and light, but it simply knows how to stand out, and I don’t mean this as a compliment.

Appearances aren’t everything, though, are they? While Oura may be prettier than the Slim Ring, the Circular Slim was way more comfortable than Oura. Plenty of times, I had to confirm if I was even wearing the ring or not because it’s so lightweight that I simply couldn’t feel it on my finger!

Remember the Circular ring’s flat bottom I told you about? It’s not there just for the looks of it. The flat surface not only has two charging rails, but it also prevents the ring from rotating around my finger, as most smart rings, including Oura, do, thereby leading to inaccurate readings at times. So, the Circular Ring pretty much stayed in the same position.

But I wish the makers of the Circular ring hadn’t simply focused on keeping the ring light and thin. You see, my Oura ring is made of durable titanium and also has a PVD coating on top of it. While this doesn’t completely make it scratch-proof, it does make it way more durable than Circular Slim.

Because Circular Slim is made of aluminum and carbon fiber (the secret of its light weight), it gets scratched very easily in comparison to Oura.

Within just a month of wearing the Circular Slim, the ring had more scratches than my Oura had in six months of usage. Before you ask, no, I didn’t put either of the rings through extreme tests like rock climbing while wearing them. The wear and tear that I noticed comes from normal everyday chores.

What’s worse is that the paint of the Slim Ring started coming off from its sides, revealing silverish metal underneath, and it looked ugly. Oura might be heavier and thicker, but it’s so much more durable than the Circular Slim ring.

After a while, I literally wanted to take off the Slim Ring because all those scratches and chipping paint looked absolutely hideous on my pretty manicured hand.

Battery Life & Charging

I need my devices to have long-lasting battery life. I can’t be bothered with keeping them charged all the time.

Charging DetailsOura RingCircular Ring
Official Ring Charging TimeUp to 80 minutes45 minutes
My Ring’s Charging Time80-100 minutes50-60 minutes
Official Battery DurabilityUp to 7 days5 days in Eco mode and 2 days in Performance mode
My Ring’s Battery Durability4-6 days1-2 days

Well, as you can see from the table, Oura understands me just fine. While the brand claims that I will get up to 7 days of battery life, and I only get around 4-6 days of battery life (or 3-4 days when continuous SpO2 monitoring is enabled), it is still better than what Circular Ring offers. The Slim Ring comes with possibly the lowest battery life I have seen in any smart ring.

The Slim Ring comes with two different battery modes that I can choose from: Eco mode and Performance Mode. Eco mode provides me with 5 days of battery life, whereas in Performance mode, the Slim Ring only lasts for around a day or two, with the advertised claim itself being two days!

Naturally, you’d expect me to have the ring set to Eco mode. But, hey! I’d rather not wear the ring at all. Because when Eco mode is enabled, the Slim Ring doesn’t track my sleep stages or even heart rate and lessens the data collection of other health metrics, too. If I didn’t want my health-related data to be collected, why would I wear a ring at all? This is why I have to use the Slim ring in Performance mode and have the battery run out within 2 days.

Clearly, Oura is way better than the Circular Ring when it comes to battery life. And not just that, I will choose the Oura ring in terms of charging convenience, too.

To charge my Oura ring, all I have to do is put it on the charging dock that comes along with the ring and then connect the dock to a power source via a USB C cable. I wait for the battery to get charged completely for around 80-100 minutes and then put it back on.

In fact, a lot of times, I don’t wait for the battery to get completely depleted. I keep putting the ring on the charger every now and then for 20 minutes or so. This ensures that my Oura ring is always properly charged.

In contrast, the Circular Ring’s battery is not the only problem; charging it is a huge hassle in itself, too. The charger is just a USB thumb drive that has charging contacts at one end. I have to attach the ring to these magnetic contact points and connect the other USB to a power source like a wall adapter or a laptop.

While this may sound simple enough to do, let me tell you from experience that the ring almost never gets securely attached to the USB drive; it wobbles. Plus, it takes a few tries to get it right.

So, I hope you understand why when I say that Circular Ring Slim’s charger is one of the worst chargers I have ever used. Naturally, I will prefer Oura over the Slim Ring in terms of charging and battery life any day.

Sensors

SensorsOura RingCircular Ring
PPG Sensor:white_check_mark::white_check_mark:
Temperature Sensor:white_check_mark::white_check_mark:
Accelerometer:white_check_mark::white_check_mark:
Infrared LED:white_check_mark::white_check_mark:
Red LED:white_check_mark::white_check_mark:
Green LED:white_check_mark::white_check_mark: 

Accuracy

Heart Rate Monitoring

Screenshot of HR Monitoring of Oura - Oura Ring vs Circular Ring Slim
HR Tracking Record on Circular App - Oura Ring vs Circular Ring Slim
Image Courtesy: Make Use Of

I found Oura Ring’s and the Circular Ring’s (in Performance mode) heart rate monitoring to be just about the same. However, there were times when I was simply sitting at my desk typing away on my laptop and the Circular ring would show me my heart rate to be around 120 bpm (while Oura was 60 bpm or so) for no good reason.

What I mean here is that, at times, the heart rate captured by the Circular ring felt higher than what Oura captured. However, Circular’s other metrics, like heart rate variability, resting heart rate, and heart rate max, were reliable most of the time.

While data inaccuracies didn’t happen all that frequently, they made me trust Circular’s data less than Oura’s. I have come to have blind faith in the latter.

Sleep Monitoring

Screenshot of Sleep Monitoring of Oura App - Oura Ring vs Circular Ring Slim

Smart rings were crafted to do a simple job: monitor sleep without making the wearer uncomfortable. While both the Oura and Circular Ring took care of the comfort part, there were some differences in their sleep monitoring accuracies.

Oura Ring is one of the best sleep-tracking devices out there, according to me. Yet, I went into testing the Slim Ring with a very open mind. I found out that sleep tracking in Eco mode is a joke. When in this mode, the Slim Ring can’t be bothered recording any sleep stages or helping the app provide me with sleep-related insights. Instead, it only tells me an approximate time when I went to bed and woke up. What do I even do with this information?

Sleep Monitoring Screen of Circular App - Oura Ring vs Circular Ring Slim
Image Courtesy: Reddit

However, the Performance mode of the Circular ring provided me with sleep-related data that I was able to compare with what I received from Oura.

For most things, like sleep score, total sleep duration, time in bed, sleep efficiency, RHR, etc., I found only a marginal difference between the two rings. So, I concluded that their accuracies were just about the same.

But then, there were some things like sleep stages for which I found a substantial difference; for example, the Circular ring often showed me a higher duration of light sleep or noted little to no sleep disturbances. Circular was usually more generous about these kinds of things, I guess. This is why Oura seemed more realistic to me in the data it offered.

However, I have learned that the Circular Ring plans to improve its Sleep staging Algorithm and make it nearly as accurate as polysomnography. Until then, I will trust Oura’s sleep data more.

Step Tracking

Steps have to be one of the most basic metrics for any smart wearable to track. While both the Oura and the Circular ring track my steps, much to my disliking, neither of the rings do it accurately. Both of the rings tend to award me with far more steps than I deserve.

Desk jobs and sedentary lifestyles go hand in hand. Yet, Oura would show good 3-4k steps even on the days I barely step foot out of my house and instead spend my time typing away on my laptop. The Slim Ring was delusional just the same. This is why I have fair amount of trouble believing the step count either of the rings show me.

Activity Tracking

Activity Tracking Insights on Oura App - Oura Ring vs Circular Ring Slim

Oura ring tracks my workouts automatically. And if I ever feel that the activity tracked or its duration was incorrect in any way, then I can open the app again and correct it. Furthermore, Oura gives me around a dozen activities to choose from. Hell, if I simply jump around on the trampoline in my backyard, I have the option to log that into the app as well.

Activity Metrics on Circular App - Oura Ring vs Circular Ring Slim
Circular Image Courtesy: Make Use Of

However, Circular Slim doesn’t provide activity tracking the way Oura does. It doesn’t have exercises that I can log into the app. In fact, I can’t even take the ring for a swim with me since it’s not water resistant like that.

The best Circular Slim does is to capture my Cardio points on the basis of my heart rate and VO2 Max data. Given that Circular doesn’t even let me track specific exercises the way Oura does, I have come to rely on Oura’s activity tracking data and insights more than that of the Slim Ring.

Readiness/ Energy Score

Readiness Score On Oura App - Oura Ring vs Circular Ring Slim
Energy Score on Circular App - Oura Ring vs Circular Ring Slim
Image Courtesy: The Gadgeteer

The Readiness/ Energy score is one of the most important things that any smart ring can provide a user with. While both the Oura and the Slim Ring provide me with this score, I have seen that Oura is usually more accurate than the Slim Ring.

For example, one Saturday morning, I woke up early to go for a 6km run that nearly killed me, met with my family for brunch, and friends for drinks in the evening. Naturally, I woke up dead tired on Sunday morning with a Readiness score of 64 (Good) in the Oura app but 94 (Optimal) in the Circular app, which wasn’t how I felt at all.

Specifications

SpecificationsOura Ring 3 Circular Ring Slim
MaterialDurable titanium, PVD coatingThe alloy of matte black bead-blasted aluminum and carbon fiber
Inside of the ring- hypoallergenic epoxy material
Weight4-6 grams2 grams
Thickness2.55mm2.2mm
Width7.9mm8.8mm
Size6 to 136 to 13
Colors availableBrushed titanium, Rose Gold, Gold, Stealth, Silver, BlackMatte black
ChargerCharging dockUSB-C Male connector
Battery LifeUp to 7 daysUp to 5 days
Charging TimeUp to 80 minutes45 minutes
ConnectivityBluetooth Low-Energy (Bluetooth Smart®)Bluetooth Smart® (Low Energy)
Compatible With Other AppsYesYes
Water Resistance– Upto 100m/ 328 ft.
– IP54
– IP68
– Up to 5m, not more than 30 minutes
– Not to be used in salty water
AI Wellness AssistanceNoYes
Vibration Alarm ClockNoYes
Medicines ReminderNoYes
EMF- safeYesNo
Airplane modeYesYes
Free Sizing kitYes (Free)Yes (Free)
FSA/ HSA eligibilityYesNo
Price$299 – $549 USD€264 (or ~$285.94 USD)
Memory7 days of data (also depends on the frequency of use)Up to 20 days of data
Compatibility– iOS devices running on iOS 15 or above
– Android devices running on Android 8.0 or higher
– iOS 11.0 or later
– Android 6.0 or later
WarrantyOne year from the date of purchaseOne year
Operating Temperature-10–52°C / 14–125°F.– Usage: -10°C / 45°C
– Charging temperature 10°C – 45°C
– Discharging temperature 20°C – 60°C

Features

FeaturesOura Ring 3Circular Slim
Heart Rate:white_check_mark::white_check_mark:
Heart Rate Variability (HRV):white_check_mark::white_check_mark:
Resting Heart Rate (RHR):white_check_mark::white_check_mark:
Workout heart rate:white_check_mark::white_check_mark:
Circadian Rhythm:x::white_check_mark:
Blood oxygen levels (SpO2):white_check_mark::white_check_mark:
Sleep tracking:white_check_mark::white_check_mark:
Detailed sleep analysis:white_check_mark::white_check_mark:
Nap detection:white_check_mark::white_check_mark:
Sleep Debt:x::white_check_mark:
Bedtime Guidance:white_check_mark::x:
Respiration Rate:white_check_mark::white_check_mark:
Skin Temperature:white_check_mark::white_check_mark:
Steps:white_check_mark::white_check_mark:
Timer:x::white_check_mark:
Calories:white_check_mark::white_check_mark:
Active Minutes:x::white_check_mark:
Distance Traveled:white_check_mark::white_check_mark:
Activity tracking :white_check_mark::white_check_mark:
Automatic activity detection:white_check_mark::white_check_mark:
Manually add activities:white_check_mark::x:
Activity Intensity:white_check_mark::white_check_mark:
Workouts:white_check_mark::white_check_mark:
Trends:white_check_mark::x:
Readiness /Energy Score:white_check_mark::white_check_mark:
Energy Monitoring:x::white_check_mark:
Rest Mode:white_check_mark::x:
Cycle Insights:white_check_mark::x:
Period Prediction:white_check_mark::x:
Pregnancy tracking:white_check_mark::x:
Fertility & Ovulation Prediction:white_check_mark::x:
Illness Detection:white_check_mark::x:
Vitals Alert:x::white_check_mark:
Health Reports:white_check_mark::white_check_mark:
Set Personalized Goals:white_check_mark::x:
Personalized Wellness Assistance:x::white_check_mark:
Guided Sessions:white_check_mark::white_check_mark:
Stress:white_check_mark::white_check_mark:
Recovery:white_check_mark::white_check_mark:
Chronotype:white_check_mark::white_check_mark:
VO2 Max:white_check_mark::white_check_mark:
Cardiovascular Age (CVA):white_check_mark::x:
Body Clock:white_check_mark::x:

One thing that I liked about both the Oura Ring 3 and Circular Slim was that they offer live tracking features. Oura can track heart rate in real time, whereas, the Slim Ring is capable of tracking heart rate, HRV, SpO2, and activity intensities live.

Companion Apps

Home Screen UI of Oura App - Oura Ring vs Circular Ring Slim

I’ll save you the trouble of reading the whole comparison: the Oura app is way better in comparison to the Circular app.

I open the Oura app first thing upon waking up. Since I have finally started prioritizing my well-being, I plan my day on the basis of the Readiness scores that the Oura app provides me with. In fact, the amount of work I will be willing to take on for the day is going to be based on what the different numbers (Readiness, sleep, stress, etc.) on the home screen look like. So, basically, a quick scroll through Oura’s cool, dark-themed home screen tells me everything I need to know.

Home Page UI of Circular App - Oura Ring vs Circular Ring Slim
Image courtesy: Trusted Reviews

I don’t share the same sentiment about the Circular app. When I open the app, it takes forever (two minutes that feel like forever) for the data to sync from the ring to the app. Only once has that happened can I actually get to see anything related to my health? On a lot of days, I don’t feel like waiting that long when I know there are other rings (like the Oura of course) that will sync up pretty quickly and show me highly reliable data then.

But, for the sake of testing the apps, I did wait.

Wanting to stay connected to its name, the Circular app shows me my health-related data in little animated circles at the top. One look at those circles gives me an idea of how I am faring for the day. Unlike Oura, the Circular app gives me two different themes to choose from: light and dark. Although I usually prefer the dark theme, I liked the Circular app better in the light theme.

What stood out to me the most was that although the Circular app has these little scores for almost everything, it doesn’t have one for Wellness scores. This score is present in a tiny box below the circles.

Oura app is better when it comes to data presentation and ease of use. When I first started using the Circular app, it felt cluttered and took me a while to get used to. Oura presented my health-related data in several different ways, and all of them were quite easy to understand.

However, the Circular doesn’t offer me such options. For example, if I want to look at my data for the week, the Circular app will simply present me with that data day-wise for that particular week.

Furthermore, the Circular app felt bugged a lot of times, too. It would keep showing me notifications that I didn’t know what to make out of. For example, it would tell me I was offline when I wasn’t. I have never had such troubles with the Oura app; the experience has always been butter-smooth and even enjoyable.

A really helpful thing about the Oura app is that it works with other apps like Strava, Clue, etc. So, if I ever forget to log in a run on the app accurately, I can simply pull that data from Strava and have it on Oura.

And I can’t even begin to tell you how grateful I am that Oura works with Natural Cycles. This incredible combination helps me take care of my cycle and moods in a way I have never before. If I am feeling particularly gutted for no good reason, Oura will tell me that it’s probably because my period is on the way.

The Circular app only allows me to sync my data with Apple Health and Google Fit, and that’s about it. I can’t pull my data from any other app I use. Forget that. The app doesn’t even let me track my menstrual cycles, and that’s the biggest downside of using the ring for any woman, not just me.

Prices, Subscription & Availability

While the Oura seems like the best thing to own, let me tell you, it may not be the most affordable as well. I got my Heritage black Oura for $299, and that’s just the starting price for the ring. Had I chosen a different style or even a different color of the same ring, this number could have gone further up.

Although I love the black color ring I have, I like the Stealth one even better. It’s a matte black-grey thing and looks absolutely gorgeous. However, it would have cost me $399, a whole $100 extra, and so I stuck with my black ring only.

On the other hand, the Circular Ring Slim cost me €264, which is roughly equal to $286.5. In fact, had I chosen the without-vibration variant of the Slim Ring, the price would have gone down to €217 or approximately $235.47. Furthermore, with the companion app being free, the Circular Ring looks pretty affordable.

Given all this, I have concluded that the one major difference between Oura and Circular Ring Slim, is their price. Because apart from that, I have found the rings to be pretty much the same.

Pricing DetailsOura Ring 3Circular Slim Ring
Official Price$299-$549– Ring with Vibration: €264 (or ~ $286.51)
– Ring without Vibration: €217 or ~$235.47
Discounted PriceN/AN/A
Subscription$5.99 a month/ $69.99 a yearFree
Sizing KitFreeFree

But please don’t think that €264 (or ~ $286.51) is all you will ever have to pay for the Circular Ring. For example, if you want to get an extra charger, that will cost an additional €25,00 or approximately $27.

Since the Circular ring’s original charger is pretty frustrating, you might be tempted to buy a USB-C extension cord for the Circular charger you have, but that will cost you an additional €12 (~ $12.99). I didn’t want to pay extra, so I decided to roll with the frustration.

And yes, even without these additional accessories, the Oura costs me more than the Circular Ring. The Oura ring itself is around $15 more expensive than the latter, but let’s overlook that. Instead, let’s talk about the Oura app subscription; it costs about $6 a month or around $72 a year. I am rolling with the monthly subscription right now.

While the idea of free apps is quite appealing, I really don’t mind paying $6 a month for the Oura app, given how helpful it is for me. Honestly, three days of my coffee costs more than that. So, the app is obviously worth it. Girl Math, baby.

Final Verdict

With all this being said, given a choice between the Oura Ring and the Circular Ring Slim, I will choose the Oura Ring with my eyes closed. Like many other rings in the market, Circular Ring tries hard to prove that Oura can’t be the only one to have a monopoly over the smart ring market. But, it fails.

I should be able to put on a ring and forget all about it. My ring should be strong enough not to get scratched easily. When I open the companion app, I should be able to trust the numbers and related insights I see blindly. The Oura ring does all this.

But I have to carefully manage the Circular ring and also constantly question what the app shows me. Will I blindly recommend the ring to someone? I don’t think so.

Frequently Asked Questions

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