The market for smart rings has grown a lot in the last few years. Devices like the Oura Ring and the Samsung Galaxy Ring have raised the bar for tracking health and fitness. The Circular Ring 2 is a bold competitor from the French tech company Circular. It was shown off at CES 2025 and is now available for pre-order on Kickstarter. The Circular Ring 2 wants to be better than its competitors by offering advanced health features like an FDA-approved ECG, free access, and a new digital sizing tool. But does it live up to what people say? Here’s a full review of the Circular Ring 2 after looking at its features, design, and first impressions.
Design: High-end and polished
The Circular Ring 2 is very different from the Circular Ring Slim, which was criticized for feeling plasticky and being easy to scratch. Circular has answered these worries by making the outside of the phone sleek and all-titanium, with four finishes: gold, silver, black, and rose gold. The ring is only 2 grams, so it’s light and comfortable to wear all day, even though the sensors on the inside band stick out a little.
The Circular Ring 2 has an IP68 rating, which is better than the Slim’s IPX8 rating. This means it can be hand washed and showered, but not swum in. The design feels high-end, and reviewers say that its more refined look is more in line with high-end competitors like the Oura Ring 4. People love the jet-black version the most, but the gold finish is a close second because it looks so classic. Some people have said that the ring’s fully enclosed loop design doesn’t have the original Slim’s unique haptic feedback motor. Circular plans to bring this feature back in a different product line.
Features: Full of Health-Tracking Power
The Circular Ring 2 has a lot of health-tracking features, making it one of the most feature-rich smart rings available. The onboard ECG sensor with FDA-approved atrial fibrillation (AFib) detection is what makes it stand out. This is the first time this has been done in smart rings. This puts it up against high-end smartwatches like the Apple Watch and Samsung Galaxy Watch, which give users real-time heart health information that could save their lives if they are at risk of heart problems.
The ring keeps track of more than 140 biometric markers, such as heart rate, heart rate variability (HRV), SpO2, skin temperature, stress, sleep stages, and activity metrics like steps, distance, and calories burned. It checks your heart rate every two minutes, which is said to be five times more often than a normal wear racket. Circular also says that by the end of 2025, updates will add blood pressure monitoring (through Pulse Transit Time) and by the end of 2026, blood glucose trend tracking. However, the latter will not replace medical-grade devices. These new features could give the Ring 2 an edge over competitors like Oura and Samsung, which don’t have them yet.
Kira, the ring’s AI-powered assistant, looks at data and makes health suggestions that are specific to you. For example, it might suggest that you cut down on screen time before bed to sleep better. The Ring 2 calibrates in just four days, which is much faster than the previous model, which needed a 14-day calibration period. This makes it easier to use. The Circular app, which works on both iOS and Android, has been redesigned to be clearer, but some users still think it is too busy and not as easy to use as Oura’s.
Sizing: A Big Deal
The digital sizing tool on the Circular Ring 2 is one of its most innovative features. It replaces the plastic sizing kits that Oura and Samsung use, which are a waste of money. The tool can measure your finger size with 95% accuracy in seconds by using a smartphone camera and a reference object like a credit card. This solves a big problem in the smart ring business, making it easier and more environmentally friendly to buy one. The ring comes in sizes 6 through 13 in the US, so it will fit a lot of people.
Charging and battery life
Circular’s earlier models had problems with battery life; for example, the Slim only lasted about two days in performance mode. The Circular Ring 2 promises big improvements, like lasting up to six days in performance mode and eight days in eco mode, which means it doesn’t need to collect data as often. Some sources, on the other hand, say that the battery life is an ambitious 12 days, which doesn’t seem to match up with official reports and may be a sign of marketing hype.
The way it charges has also been improved. The Ring 2 replaces the Slim’s small USB-C charger with a wireless charging dock, which is easier to use and less likely to lose parts. This makes it more like competitors like the Oura Ring 4, which also charges by docking.
How well it works and how accurate it is
Early tests show that the Circular Ring 2’s improved sensor array, which includes more photoplethysmography (PPG) sensors, tracks health more accurately than the Slim, which was criticized for making mistakes like counting steps off by up to 5,000. The heart rate, SpO2, and sleep tracking on the Ring 2 are now said to be as good as those on the best smart rings, but full reviews are still needed to confirm these claims.
But Circular’s past makes some people doubt it. The first Slim had problems with syncing and data that wasn’t always right, and some users said their devices wouldn’t connect or sync with the cloud. Circular says it has fixed these connection problems with the Ring 2 and promises that background syncing will work without any problems. It’s hard to say if these improvements will last until long-term testing is done.
Cost and Availability
The Circular Ring 2 costs $349 for early backers on Kickstarter, but it will cost $380 to $549 at retail, depending on the finish. This is a good deal compared to the Oura Ring 4 ($349) and the Samsung Galaxy Ring ($399), especially since Circular doesn’t require a subscription like Oura does for $5.99 a month. You can pre-order on Kickstarter, and the items should ship in June 2025.
People are worried about Circular’s reliance on crowdfunding, though. Some people who backed the first Circular Ring had to wait a long time and had problems with customer service. The company’s switch to a white-label model with an Asian manufacturer makes people wonder if the Ring 2 is a truly new product or just a rebranded version of the Linktop Cardio Ring. Being open about this partnership could help people trust you again.
The Competition
The Circular Ring 2 comes into a market that is already full. The Oura Ring 4 is still the best choice because it gives you useful health information and has a polished app, but the subscription model is a downside. The Samsung Galaxy Ring has great tracking, but it’s only for Android, which makes it less appealing. The Ultrahuman Ring Air has many of the same features as the Circular, but it doesn’t have the Circular’s digital sizing tool. It does have AFib detection as a paid add-on. The RingConn Gen 2 Air costs $300 and is a good choice for people on a budget. It has a long battery life but fewer advanced features.
The Circular Ring 2 has ECG capability, digital sizing, and a no-subscription model that set it apart. However, it needs to compete with the Slim, which has a bad reputation for accuracy and reliability.
First Thoughts and Worries
Reviewers have said that the Circular Ring 2 is the best smart ring at CES 2025, and the hands-on demos have been very positive. People like its titanium construction, comfortable fit, and new sizing tool. The ECG feature makes it stand out in a market where health tracking is getting more advanced.
But there are some warning signs. Because Circular has a history of making promises it can’t keep, like saying batteries would last longer than they do or that syncing problems would be fixed, it’s hard to believe that it can deliver. The fact that the company didn’t send the Ring 2 to reviewers for full testing before its Kickstarter campaign shows that they are being careful about how they manage expectations. Also, claims that the Ring 2 could be a rebranded device instead of a new product made by the company could hurt its credibility.
Verdict: A Strong Candidate with Some Issues
The Circular Ring 2 is a big step forward. It fixes a lot of the Slim’s problems with a high-end titanium design, advanced health features like ECG and AFib detection, and a new digital sizing tool. It has no subscription fees and prices that are competitive, which makes it a good choice over the Oura Ring 4 and the Samsung Galaxy Ring. But Circular has a lot to prove because of its bad track record with reliability, customer service, and openness.
The Circular Ring 2 is worth a look if you’re interested in its features, especially if you were one of the first backers and paid $349. But since shipping isn’t expected until June 2025 and full reviews are still pending, it’s a calculated risk. If Circular keeps its word, the Ring 2 could change the smart ring game. For now, be cautiously optimistic and look for full reviews once the device is sent out.
