The smart ring market isn’t heating up, it’s on fire with so many brands now getting into the space. As an less distracting alternative to a smartwatch or a viable supplement to it, you’ll notice these rings around plenty of fingers nowadays, present company included. Circular has introduced a few models to date, including the Circular Ring Slim I reviewed in mid 2024. After introducing the Circular Ring 2 as a concept at CES 2025 early last year, the device is finally available. And it sets itself apart from others in being able to take ECG and check for Afib, right from your finger.
The Circular Ring 2 from the French company achieved more than US$4 million in crowdfunding to help bring it to market. Along with ECG-based heart rhythm monitoring, it also offers Afib detection and AI-powered health coaching. Other smart rings, like the Ultrahuman Ring Air, offer things like Afib detection but that feature requires a subscription. The best part about these features in the Circular Ring 2 is that they don’t require one.
Returning for the Circular Ring 2 is the Kira AI health coach that guides you along each day. The ring analyzes more than 140 biomarkers to deliver personalized and actionable recommendations. After a 14-day calibration period, Kira begins to learn more about your habits, sleep, activity, stress, and overall lifestyle patterns and provides tailored advice, like how to optimize your sleep, better manage stress, or improve recovery. Smart motivations are provided through gamified progress in the form of Circular Coins along with celebrations when you hit milestones. Using the global monthly leaderboard, you can compete with the Circular community for even more motivation, with rankings that reset monthly and Circular Coins that unlock real-life benefits.
The ECG-based heart rhythm analysis uses a validated algorithm designed to identify irregular heart rhythms, including atrial fibrillation (AFib). In just 30 seconds, you can access insights and receive alerts when irregular patterns are detected.
The smart ring uses advanced sensors, including PPG (red, green, infrared), skin temperature, and a three-axis accelerometer to deliver high-precision, continuous health monitoring from the finger. Along with the aforementioned data, you get detailed sleep analysis and sleep cycles, energy and recovery analysis, stress and coherence tracking, heart rate and resting heart rate, heart rate variability, blood oxygen, breathing rate, temperature trends, steps and cardio points, sports sessions and activity detection, VO2 max estimates, and women’s health insights. All insights are accessible through the Circular app, which has been completely redesigned for a more intuitive experience.
The ring lasts for up to seven days per charge in Eco Mode, four days in Performance Mode, and can full recharge in 30 minutes. The lower battery life in performance mode (which, if this is anything like performance mode in the Circular Ring Slim, you’ll want to use) may be attributed to the fast data refresh rate, which Circular says is every two minutes. The Ring is durable as well with an IP68 rating. It comes with Bluetooth Smart with airplane mode, multi-device support, and the ability to connect up to two rings to a single account.
Circular Ring 2 includes a wireless charging dock. Made from hypoallergenic titanium, it comes in Obsidian Black (US$349), Silver (US$449), Gold & Rose Gold (US$549).
It’s worth noting that in 2024, Circular entered into a multi-year patent license agreement with Oura, granting the company the “right to continue developing, selling, and supporting its smart rings and associated applications on a long-term basis, subject to ongoing royalty payments.”
“Oura revolutionized wearable technology with the introduction of the smart ring over a decade ago,” says Amaury Kosman, Co-Founder and CEO of Circular. “We recognize the strength of foundational patents in this category, and this agreement enables Circular to continue innovating confidently while delivering advanced health technology to users worldwide.”