The most ambitious smart ring on paper — on-finger ECG, AFib detection and an AI coach, all subscription-free — but the software is unfinished, and the headline health features didn’t reliably work in independent testing.
Best for early adopters excited by on-ring ECG/AFib and AI coaching who accept that the software is unfinished. Everyone else should wait for it to mature.
The Circular Ring 2 is the boldest hardware pitch in the category: the first smart ring with an on-finger ECG sensor and atrial-fibrillation (AFib) detection, paired with "Kira," a subscription-free AI coach that reads 140+ biometric markers after a 14-day calibration. On paper it combines ECG + AFib + proactive AI + zero subscription in a way no other ring does. In practice, independent 2026 reviews found the software got in the way — the ECG and AFib monitoring never fully worked during testing, and promised blood-pressure and glucose features had not arrived. Battery is about six days. It’s a genuinely innovative ring whose ambition currently outruns its execution.
Как мы оценивали: Evidence-based assessment — scored from Circular specifications and independent 2026 reviews, which flagged significant software problems. Not hands-on tested by ONDA.
HRV tracking is present, but overall data reliability was uneven in independent testing.
Качество сенсора и сигнала
7.5
The most ambitious sensor array in a ring — on-finger ECG and AFib detection. The hardware is real; the problem is the software driving it.
Точность отслеживания сна
6.5
Standard sleep tracking, undercut by the app’s overall roughness.
Доступ к данным и экспорт
6.0
Data lives in the Circular app with the Kira AI layer; no truly open API.
Носибельность и батарея
6.5
About six days of battery (eight claimed); comfortable to wear, in multiple finishes.
Приложение и софт
5.5
The weak point. Independent reviewers found the software buggy and unfinished — the ECG/AFib features didn’t reliably work, and promised blood-pressure and glucose tracking hadn’t shipped.
Цена и ценность
6.0
From $349 (higher finishes cost more), subscription-free. Fair only if you’re buying the potential — the marquee features don’t yet fully deliver.
Плюсы
+First smart ring with on-finger ECG and AFib detection
+Subscription-free, including the Kira AI coach
+Genuinely innovative hardware ambition
+Multiple finishes; ~6-day battery
Минусы
−ECG/AFib monitoring did not reliably work in independent testing
−Buggy, unfinished software
−Promised blood-pressure and glucose features not yet shipped
−Data reliability uneven; no open API
Цена: $349 Obsidian Black; Silver $449, Gold/Rose Gold $549; subscription-free (по состоянию на 2026-09-06)
Where it leads
No other smart ring is this ambitious. The Circular Ring 2 puts an ECG sensor on your finger with atrial-fibrillation detection — a first for the category — and pairs it with "Kira," a subscription-free AI coach that reads 140+ biometric markers and personalises after a 14-day calibration. The combination of ECG, AFib, a proactive AI and no subscription genuinely doesn’t exist elsewhere.
Where it falls short
Execution. Independent 2026 reviews were clear: the software got in the way. The headline ECG and AFib monitoring never fully worked during testing, and promised blood-pressure and glucose features had not arrived. For a ring whose entire pitch is advanced heart-rhythm sensing, features that don’t reliably work are a serious problem, not a footnote.
Who it is for
Choose the Circular Ring 2 only if you’re an early adopter who wants on-ring ECG/AFib and AI coaching and accepts buying the potential rather than a finished product. If you want features that work today, the RingConn Gen 3 (subscription-free, with vascular and sleep-apnea insights that ship) or Oura Ring 5 are safer.
