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The Circular Ring 2 starts at $349 in the US and pairs a lightweight titanium design with sleep, activity, recovery, and heart-health tracking, including a single-lead ECG sensor. Its core tracking has no mandatory subscription, but the app has drawn reliability complaints, and blood-pressure and glucose features should not be treated as established, broadly available functions. It suits buyers drawn to ECG hardware and subscription-free basics more than anyone who needs proven medical monitoring or a polished software experience.
Price and availability
Circular’s US store lists the Ring 2 from $349 for the base finish. A physical sizing kit costs an additional $5 when selected at checkout, and Circular advertises HSA/FSA eligibility with documentation for qualifying buyers. TechRadar reported a finish-based US price ladder of $349 for black, $449 for silver, and $549 for rose gold or gold; check the finish and final checkout price, since those figures may vary by promotion or configuration. Circular’s product page is the reference for current ordering details.
The Ring 2 followed a 2025 Kickstarter campaign and reached customers during late 2025 and 2026. Circular’s regional page advertises free 14-day returns, a one-year warranty, worldwide shipping for qualifying orders, and 24/7 support; terms and delivery estimates can vary by country, so verify the specific terms shown for your order. The page has also carried a 10–15 day delivery notice tied to Middle East transit disruptions, which should not be assumed to apply to all US orders. Circular’s regional Ring 2 page
Specs at a glance
| Specification | Circular Ring 2 |
|---|---|
| Exterior and interior | Titanium exterior with coating; non-allergenic, non-metallic clinical-grade biocompatible epoxy interior, according to Circular’s user guide |
| Weight and dimensions | About 3 g; 7.8 mm wide and 2.55 mm thick |
| Sizes | US whole sizes 6–14; no half sizes listed |
| Sensors | Single-lead ECG, PPG/oximeter, digital temperature sensor, and 3-axis accelerometer |
| Connectivity and storage | Bluetooth Low Energy 4.2–5.0; up to seven days of onboard storage depending on use and recording frequency |
| Battery | 14.5–21.5 mAh rechargeable, non-replaceable lithium-ion battery |
| Charging | Wireless charging case and USB-C cable included |
| Water resistance | IP68; user guide specifies immersion up to 50 m for 30 minutes |
| App compatibility | iOS and Android |
These technical details come from Circular’s user guide and its product page. Circular’s retail page claims up to eight days in Power Mode or five days in Performance Mode, while the user guide lists up to seven days. The retail page estimates about 30 minutes to charge; the guide says about 60 minutes. TechRadar reported roughly six days in testing, so actual battery life and charging time can differ with mode, use, ring size, syncing, and software.
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- Advanced Sleep Monitoring: Tracks your sleep patterns and oxygen levels throughout the night, providing insights to help you understand your sleep better.
- Real - time SpO2 Tracking: Continuously monitors your blood oxygen levels in real - time, keeping you informed of your body's oxygen status. Monitors heart rate, HRV, SpO2, activity, stress, and temperature. OTA updates ensure latest features, while the app provides trend analysis and personalized insights.
- No Subscriptions, Extended Battery: One-time purchase unlocks all features permanently. 4 - 7 day battery life with 120+ additional hours from portable charging case. iOS/Android compatible with Apple Health sync. 5 ATM waterproof.
- Professional Fitness Tracking: Accuracy rivals chest straps with multiple sport modes, real-time monitoring, and customizable goals to optimize training effectiveness.
What the ring tracks
Circular says Ring 2 tracks more than 140 biosignals across 13 or more health features. Its advertised wellness functions include heart rate, resting heart rate, HRV, sleep and sleep stages, activity and steps, recovery and energy scores, breathing rate, blood oxygen, skin-temperature trends, stress and wellness insights, and menstrual-cycle-related trends. Circular also lists guided breathing or coherence exercises, medication reminders, vital alerts, and its Kira AI coach. Circular’s product page
Those features combine different kinds of information: sensors collect measurements such as movement, pulse, and temperature; software turns them into derived scores such as recovery or stress; and Kira adds recommendations based on the available data. A score or AI suggestion is an interpretation, not a clinical measurement. Check the underlying readings and treat coaching as general wellness guidance, especially if syncing has been delayed or incomplete.
Rank #2
- [AI-Powered Health Insights] RingConn Gen 2 Air Smart Ring integrates AI with multi-sensor data to continuously track key health metrics like sleep, heart rate, stress levels, blood oxygen, physical activity, and menstrual cycles. Its built-in AI assistant delivers your personalized report and guidance to enhance your wellness and daily habits
- [Size Before You Buy] RingConn Gen 2 Air uses unique sizing standards, different from standard ring sizes. Purchase RingConn Sizing Kit to find the most accurate and comfortable fit for your finger
- [No-Feel Wearing] Experience a comfortable, stylish design with a super-thin 2mm profile and only 2.5g weight. Won't interfere with your movement whether you're working out, running, diving, or engaging in any physical activity, and stays comfortable without distracting you when sleeping or working
- [No Subscription Fee for Standard Features] Unlock the lifetime use of essential standard features on the RingConn Smart Health Monitoring App with your RingConn Gen 2 Air Smart Ring. Experience continuous, real-time health tracking and personalized insights
- [Longer Battery Life] Enjoy up to 10 days of uninterrupted power with a single full charge that completes in just 90 minutes. Stay powered through your busy schedule without frequent recharging and efficiently maintaining continuous long-term data collection
ECG and AFib: what to expect
The ring has a single-lead ECG sensor as well as PPG sensors. Circular markets on-demand heart-rhythm recordings and AFib-related analysis as a key differentiator. However, a sensor in the ring does not by itself establish that a feature is reliable or that it can diagnose a condition. In its June 2026 review, TechRadar reported that ECG and AFib monitoring did not work consistently during its testing.
Do not use the Ring 2 as a substitute for a clinical ECG, medical assessment, emergency care, or a medical-grade continuous monitor. If you have chest pain, fainting, severe shortness of breath, concerning palpitations, or other urgent symptoms, seek medical care rather than waiting for a ring reading.
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Rank #3
- [AI-Powered Health Insights] RingConn Gen 2 Air Smart Ring integrates AI with multi-sensor data to continuously track key health metrics like sleep, heart rate, stress levels, blood oxygen, physical activity, and menstrual cycles. Its built-in AI assistant delivers your personalized report and guidance to enhance your wellness and daily habits
- [Size Before You Buy] RingConn Gen 2 Air uses unique sizing standards, different from standard ring sizes. Purchase RingConn Sizing Kit to find the most accurate and comfortable fit for your finger
- [No-Feel Wearing] Experience a comfortable, stylish design with a super-thin 2mm profile and only 2.5g weight. Won't interfere with your movement whether you're working out, running, diving, or engaging in any physical activity, and stays comfortable without distracting you when sleeping or working
- [No Subscription Fee for Standard Features] Unlock the lifetime use of essential standard features on the RingConn Smart Health Monitoring App with your RingConn Gen 2 Air Smart Ring. Experience continuous, real-time health tracking and personalized insights
- [Longer Battery Life] Enjoy up to 10 days of uninterrupted power with a single full charge that completes in just 90 minutes. Stay powered through your busy schedule without frequent recharging and efficiently maintaining continuous long-term data collection
Blood pressure and glucose: promised features, not dependable buying reasons
| Feature | Status and qualification |
|---|---|
| Blood-pressure estimation | Circular describes an approach using PPG and ECG data with Pulse Transit Time. Its July 2026 community update said development was about 90% complete and worldwide rollout was still pending; it planned a free version and a later premium tier. TechRadar reported the feature was unavailable in its June 2026 test. |
| Glucose trends | Circular labels this a planned 2026 premium feature. TechRadar found it unavailable in June 2026. Launch timing, supported countries, price, accuracy, and clinical validation are not established here. |
Check the app and feature availability for your country before buying; a staged rollout may depend on app version, firmware, and region. Blood-pressure estimation is not a replacement for a validated upper-arm cuff. Glucose trends would not make the ring a continuous glucose monitor and must not be used to dose insulin or manage diabetes in place of approved testing or medical advice. Circular’s product page, Circular’s July 2026 community update, and TechRadar’s June 2026 review
App, syncing, and ongoing software risk
A screenless ring depends on its app to show readings, explain trends, and deliver much of its value. TechRadar and Android Central described slow or failed syncing and an app they found cluttered or unintuitive, with information spread across screens. That makes software quality a central consideration rather than a minor inconvenience. TechRadar’s review and Android Central’s review
Rank #4
- [Sleep Apnea Monitoring] RingConn Gen 2 Smart Ring supports sleep health with advanced technology. Developed with leading universities and hospitals, this AI-powered ring accurately tracks sleep apnea. Unlike traditional devices, it's lightweight and comfortable, offering multi-day monitoring with real-time AHI data and personalized insights via a dedicated app for easy sleep health management
- [Size Before You Buy] RingConn Gen 2 Smart Ring uses unique sizing standards, different from U.S. and other health rings. RingConn Gen 2 Sizing Kit helps you find the most comfortable and accurate fit for your finger, preventing the inconvenience of returns and exchanges by ensuring you select the correct size before purchasing
- [No Subscription Fees] Unlock lifetime access to the comprehensive suite of features on the RingConn Smart Health Monitoring App with your RingConn Gen 2 Smart Ring. Experience continuous, real-time health tracking and personalized insights
- [More Than Just Health Monitoring] RingConn Gen 2 Smart Ring surpasses standard health monitoring features by not only tracking your activity, sleep, stress, heart rate, HRV, and blood oxygen saturation but also supporting OTA updates. This ensures continuous improvements and the addition of new features, delivering an ever-evolving experience tailored to your needs
- [Waterproof for Every Adventure] RingConn Gen 2 Smart Ring features upgraded water resistance of up to 100m, making it perfect for daily wear, workouts, and swimming. Plus, RingConn Gen 2 offers outstanding durability with a gentle touch, even for sensitive skin
Circular’s July 2026 community update said app and firmware changes, including firmware 1.6.3, reduced sync crashes from about 5% of users to 0.2%. That is a company-reported statistic, not an independently audited result, and it does not establish that all syncing issues are resolved. Before ordering, check recent App Store and Google Play reviews. Cloud syncing and later software updates can also affect how promptly data appears and how app features behave.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Subscription, premium features, and Circular Coins
Circular says core health features and biometrics are included without a mandatory subscription. Its pages also describe optional paid access for some advanced features and a model in which users may spend Circular Coins earned through daily use. Blood-pressure functionality has been described as having free and premium tiers, while glucose trends are planned as premium. The exact cash price for premium access is not stated in the cited first-party material. Circular’s product page and feature page
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- [AI-Powered Health Insights] RingConn Gen 2 Air Smart Ring integrates AI with multi-sensor data to continuously track key health metrics like sleep, heart rate, stress levels, blood oxygen, physical activity, and menstrual cycles. Its built-in AI assistant delivers your personalized report and guidance to enhance your wellness and daily habits
- [Size Before You Buy] RingConn Gen 2 Air uses unique sizing standards, different from standard ring sizes. Purchase RingConn Sizing Kit to find the most accurate and comfortable fit for your finger
- [No-Feel Wearing] Experience a comfortable, stylish design with a super-thin 2mm profile and only 2.5g weight. Won't interfere with your movement whether you're working out, running, diving, or engaging in any physical activity, and stays comfortable without distracting you when sleeping or working
- [No Subscription Fee for Standard Features] Unlock the lifetime use of essential standard features on the RingConn Smart Health Monitoring App with your RingConn Gen 2 Air Smart Ring. Experience continuous, real-time health tracking and personalized insights
- [Longer Battery Life] Enjoy up to 10 days of uninterrupted power with a single full charge that completes in just 90 minutes. Stay powered through your busy schedule without frequent recharging and efficiently maintaining continuous long-term data collection
In practice, “subscription-free” means no required recurring fee for the core feature set; it does not guarantee that every future or advanced function will be included at no extra cost.
Fit, charging, and water resistance
Choose the size carefully
Circular lists nine whole US sizes, 6 through 14, with no half sizes. It offers an app-based sizing process and an optional $5 physical sizing kit. Finger size changes with temperature, activity, and time of day: a ring that is too tight can be uncomfortable, while one that is too loose may compromise sensor contact. Use the sizing process before ordering and take extra care if you fall between sizes.
Charging case and water
The wireless charging case is included, but the case is not waterproof. Circular’s user guide says it is for indoor use and can be damaged by moisture. The guide specifies IP68 protection for the ring, with immersion up to 50 m for 30 minutes; this does not establish suitability for scuba diving or high-pressure water exposure. Circular’s user guide
Who should buy the Circular Ring 2?
It may suit you if
- You want a lightweight titanium ring for sleep, activity, recovery, and general wellness trends.
- You value ECG hardware and are comfortable with the limitations and software uncertainty reported so far.
- You prefer no mandatory subscription for core tracking.
- You can tolerate an app that may be less polished than established alternatives, and you are willing to check recent user feedback and feature availability.
Consider another option if
- You are buying mainly for blood-pressure or glucose tracking; neither should be assumed to be broadly available or suitable for medical decisions.
- You need dependable clinical monitoring, highly polished software, mature sports features, or an established ecosystem.
- You need a half size or cannot accept sizing and fit uncertainty.
- You would be uncomfortable depending on a smaller company’s app, cloud services, firmware updates, support, and delivery of promised features.
Alternatives to compare
The right comparison depends on whether you value an established wellness app, phone ecosystem, subscription-free basics, or Circular’s ECG-centered approach. Verify current plans and prices directly, since they are not compared here.
| Alternative | Worth considering if… | Trade-off to check |
|---|---|---|
| Oura Ring | You prioritize a mature app and a polished sleep and recovery ecosystem. | Review membership and subscription terms. |
| Samsung Galaxy Ring | You use Samsung Galaxy devices and value integration with that ecosystem. | Its strongest fit may depend on compatible Samsung devices. |
| RingConn | You want a subscription-free smart-ring alternative with a battery-life focus. | Its app and feature priorities differ from Circular’s ECG pitch. |
| Ultrahuman Ring AIR | You want another subscription-free option focused on lifestyle, recovery, and metabolic insights. | It does not offer the ECG-centered differentiator described for Circular Ring 2. |
Verdict
Circular Ring 2 is an ambitious $349 smart ring whose best case is a lightweight build, broad wellness tracking, ECG hardware, and no mandatory fee for core features. Its weaker case is the gap between that hardware promise and the software experience reported by reviewers, alongside health features whose availability or maturity remains uncertain. Buy it for the core tracking and ECG potential only if you accept those limits—not on the assumption that blood-pressure or glucose monitoring is ready to rely on.
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
