Circular Ring 2 review: Breaking new smart ring ground

Best Prices Today: Circular Ring 2

The Circular Ring 2 is a smart ring that isn’t satisfied with simply being an alternative to the Oura Ring 4 without the added subscription. This is a ring that wants to break new ground in terms of what a smart ring can be capable of.

This the first smart ring to include an ECG sensor, with blood pressure insights and glucose trends on the way too. This is a smart ring that doesn’t just want to make up the numbers.

Circular’s previous efforts have failed to impress, however. But with uncertainty hanging over some of its rivals due to patent disputes with Oura, could Circular steal a march and become the smart ring to get instead of Oura?

I’ve been wearing the Ring 2 for a month now to find that out.

Design & Build

• Available in four colours
• IP68 water resistance
• Comes with portable charging case

The Ring 2 gives you a pick of obsidian black, rose gold, gold or silver colourways. In terms of sizing, Circular covers US sizes from 6-14.

There is also a digital sizing kit you can use to get the best fit, which should be one where the ring fits snug enough so that it doesn’t spin around too much on your finger to disrupt monitoring.

I had the Ring 2 in the same size as the Ring, Smart Ring Slim and a bunch of other smart rings I’ve also tested, including the Oura Ring 4 and the Samsung Galaxy Ring. It’s certainly much nicer-looking than the Circular Ring Slim. It’s also less prone to picking up scratches. Ditching the interchangeable shells from the first Ring was a good move to make.

It’s a titanium ring, matching the light yet durable metal most smart rings have opted for. There’s a nice sheen to the ring’s exterior with a sensor bump that, while it doesn’t entirely disappear, also doesn’t make it uncomfortable to wear.

There’s a small circular logo to remind you of the correct way to wear it. I’ve been wearing one on one hand and the Oura Ring 4 on the other. The size, thickness and general presence on your hands is similar. You do just notice the sensor bump less on the Oura.

Circular sticks with a design that has an IP68 rating for dust and water resistance, so that’s not the strongest level of protection against water for a smart ring, though Circular says it’s “safe for swimming, showering, and daily wear.”

It’s good to see that Circular has changed its approach to a charging solution for its latest ring. It’s ditched the small, keychain-style one it included with its Ring Slim for a charging case.

It has a very different look from the ones included with Samsung and RingConn rings. It’s done the job of keeping the ring in place during charging and offers a built-in battery to let you charge on the move. More on that in the battery life section later.

Health Features

• ECG measurements
• PPG heart rate and SpO2 tracking 
• Medication reminders

When you dive into what is a pretty busy Circular smartphone companion app (compatible with both iOS and Android), you’ll appreciate just how much is on offer with the Ring 2.

This is still a smart ring that has the required sensors to track daily activity and monitor sleep, along with metrics like heart rate and SpO2. It’s also added features to make it a better fit for use during some workouts. It now wants to keep a closer eye on tracking your emotional state, too.

Let’s start with the big one both for Circular and smart rings in general. This is the first smart ring to include an ECG sensor and features electrodes on the outside of the ring to let you take on-the-spot measurements.

Those measurements analyse heart rate rhythm and can look for irregular ones. The sensor and algorithm used to do this have both been cleared by the FDA to detect signs of atrial fibrillation.

Taking a reading is done by placing the index finger of your opposite hand on the top of those electrodes. After a 45-second measurement, the reading will be classified. Those will determine that rhythm is normal or show signs of bradycardia, tachycardia or atrial fibrillation. 

Thankfully, all of my readings detected a normal heart rate rhythm, though interestingly stated a confidence between 60-70%. Circular, like a lot of tech brands making similar wearables, states that this feature isn’t a diagnosis and doesn’t replace a medical device, despite sounding very much like a medical feature.

It will even let you generate reports to show a medical professional, so it could at least help with your health care. The readings at least looked accurate when compared to other ECG-reading devices like the Apple Watch.

Beyond ECG measurements, there’s a whole lot more on offer here. You can check live measurements of your heart rate and SpO2 levels, set up alerts for high and low heart rate or SpO2 levels (or both) and set up reminders to take medication.

I think the UI in the app needs to be cleaner and less cluttered than it currently is to make absorbing this data a lot easier.

Fitness & Wellness Tracking 

• Track steps, sleep, heart rate and emotional state
• Dedicated sports modes
• Sleep and Energy analysis insights

The Circular Ring 2 gives you what are becoming feature staples of all smart rings.

This is something you can take to bed more comfortably to track your sleep than a smartwatch. You can wear it all day and let it keep tabs on your movements and metrics like heart rate.

It does those things and more in a very good fashion. However, if you don’t sync data on a regular basis, it can seem to take an age to sync with the app.

For sleep, you’ll generate sleep scores, get a breakdown of sleep stages and it’ll record sleep duration as well. It’ll display data like sleep quality on graphs to see how that changes or maybe even remains constant.

There’s also dedicated graphs for HRV, breathing rate, temperature and SpO2 levels. I’ve been wearing it alongside two different sleep trackers. It offered pretty similar sleep duration data to devices like Oura, as well as recognising sleep start and wake-up times.

Sleep scores were similar, and when I napped, it managed to pick them up. At its core, there’s a strong sleep tracking performance.

Daily activity is broken down to steps, cardio points and will also look at metrics like VO2 Max and HR max to assess Circular’s energy scores. This score aims to give you a better sense of energy levels to tackle your day.

Sleep scores can also influence this score. Think of it like Oura’s Readiness scores and similar metrics on offer on the Google Pixel Watch 4, Samsung’s smartwatches and many Garmin watches. Looking at some of that data in isolation and daily step counts totals were pretty similar on most days compared to two other respected and reliable fitness trackers.

There is a dedicated sports tracking mode, which lets you pick from a range of sports profiles, including ones that would benefit from piggybacking off your phone’s GPS signal to better track your movements outside.

I’ve used it for outdoor runs and indoor workouts like rowing and cycling and the results have been mixed. I’ve not tested a smart ring that I really think does a good job of tracking heart rate during exercise and that hasn’t changed here.

Beyond activity, there are features on offer on the wellness front which has become more common.

A coherence mode tracks your heart rate variability to help get you into a clearer state of mind. There’s a good range of guided breathing exercises on offer on the app and a place to keep an eye on stress levels and even see predictions on stress based on previous stress data history. 

This ring doesn’t shortchange you in features, but isn’t the best at presenting them.

Battery Life & Charging

• Up to 7 days battery life
• Portable charging case
• Fully charges in 30 minutes

The Circular Ring 2’s approach to battery, much like previous Circular Rings, is an unusual one.

You have the option of battery modes – there’s Performance mode, which gets you the most accurate tracking on offer and samples data at a higher frequency than the Power battery mode.

The power saving mode samples heart rate data at a lower frequency and means you’ll also live without richer sleep data and less detailed data tracking overall.

The maximum battery life you’ll enjoy is 7 days, which is one less day than Oura, the same as the Samsung Galaxy Ring and short of the comparatively mammoth 10-12 days that the RingConn Gen 2 can keep going for. 

Like previous Circular smart rings, opting for the performance mode does see a much more noticeable drain each day. In that performance mode, the battery lasted 4-5 days. That’s better than before, but not quite as good as the best smart ring battery performers.

Additionally, there is a power saving mode, which is designed to preserve battery when you’re not using the ring for long periods and isn’t simply draining battery in between the time before you drop it into the charging case again.

You’ll get a phone notification to tell you when it’s running low and now you have a more convenient way to charge it back up. Like Samsung and RingConn, you now have a charging case that can power the ring back up in just 30 minutes.

It’s infinitely more convenient than the keyring USB stick setup of the Circular Ring Slim. It’s not fiddly, you can take it anywhere and it holds enough battery power to charge the Ring 2 three times.

Price & Availability

The Circular Ring 2 launched in August 2025 and is priced at £280/$379 for the cheapest model. Like previous Circular Rings, there’s no added subscription needed to gain full access to features and data.

However, Circular will be making some future features available through a model where you’ll need to amass a certain amount of its virtual Circular Coins currency to get them instead. You will also have the option to purchase those coins to fast-track access, which will include an upcoming blood pressure trends feature.

The cheapest price will get you the black tested here, but other models are more expensive. Silver costs £360/$449 and the two gold options are an even more sizeable £440/$549.

You can buy the Circular Ring 2 from the official store.

How does it size up to the competition? Let’s start with the best-known, the Oura Ring 4. That ring does rely on a monthly or annual subscription, plus anywhere from £349/$349 to pick up the ring.

The subscription-free Samsung Galaxy Ring sits at £399/$399, so both Samsung and Oura rings are more expensive in comparison, though Samsung doesn’t require a subscription.

The Ultrahuman Ring Air costs £329/$349 while the RingConn Gen 2 sits at $299. Those two rings at the time of writing were set to be pulled from sale in the US after Oura won a patent infringement filing against the two new smart ring newcomers. That could, of course, change in the future.

That would leave Oura, Samsung, Amazfit and Circular as the main players in the smart ring space. Samsung, though, has seen recent problems with battery swelling on the Galaxy Ring.

Should you buy the Circular Ring 2?

I tested the original Circular smart ring and I didn’t even complete my testing due to so many issues. I had more luck with the Circular Ring Slim, but it still couldn’t compete with other smart rings.

With the potential that Ultrahuman and RingConn rings could be banned from the US, that leaves a much smaller competition for the Circular Ring 2. You’ve primarily got the Oura Ring 4, Samsung Galaxy Ring and the Amazfit Helio Ring.

I would still say the Oura Ring 4 is the standout smart ring after my time with the Circular Ring 2. It’s certainly the best Circular ring I’ve tested and while Samsung’s software feels a little cleaner in comparison, Circular’s software is clearly built for a smart ring and could catch up with some time.

If you’re looking for a subscription-free smart ring, then this is certainly up there as a top option.

Specs

• Up to 7 days battery life
• ECG and Optical heart rate sensor
• Tracks blood oxygen, skin temperature 
• Tracks sleep and steps
• Titanium design
• 2.55mm thick
• Weighs 2-3g (size dependent)
• iOS and Android compatible

Best Prices Today: Circular Ring 2