The best smart rings with ECG: one ring does it, and the fine print matters

The state of play

Search for a ring with an ECG and you will find long lists. The real market is one device. Circular sells the Ring 2 from its own store at a single listed price, in US sizes 6-14, IP68, titanium with a PVD finish, and describes the headline feature as “Forty seconds at your finger, screened for atrial fibrillation, exportable as a PDF” (Circular). Its homepage calls the reading “a world first on a ring” (Circular).

Nobody else offers it. Oura, RingConn, Samsung and Ultrahuman all use optical sensing - heart rate, HRV, blood oxygen, temperature - and none of their spec sheets lists an electrical heart sensor. So the choice is not between rings with ECGs; it is between one ring with an ECG and every wrist device that has had the feature for years.

What a ring ECG actually is

An ECG measures the electrical activity of your heart, which needs a circuit across your body rather than light shone through a finger. On a ring, you complete that circuit by touching the ring's outer electrode with a finger from the other hand and holding still for the reading. That is a single-lead ECG, the same class of measurement a smartwatch takes - not the 12-lead trace a hospital records.

What a single-lead reading is genuinely good for is atrial fibrillation screening: a rhythm irregularity that can come and go, so catching one on a device you already wear is useful. What it cannot do is rule things out. A normal reading at 9am says nothing about 3pm, and neither Circular nor Apple nor Samsung claims otherwise.

This is different from what rings do with light. Our heart rate accuracy page covers the optical side, where the evidence is much richer - and where the honest summary is that rings are good overnight and poor during exercise.

The FDA question, precisely

This is where most articles on this topic go wrong, so here is exactly what we could and could not verify on 2026-09-29.

• Circular Ring 2: no FDA clearance claim appears on Circular's homepage or on its Ring 2 shop listing. We have seen third-party articles describe the Ring 2 as having an FDA-cleared AFib algorithm; we could not verify that on Circular's own pages, so we do not repeat it as fact.
• Circular Ring 3 Pro: Circular's Ring 3 page does make the claim - “ECG readings cleared by the FDA” - for the Pro model, alongside arrhythmia and AFib screening. That ring is not on sale: Circular says “Pre-orders open December 2026” and that pricing “has not been announced” ( Circular).
• The only FDA-cleared sensor on any smart ring we found is a pulse oximeter, not an ECG: Movano Health received 510(k) clearance for the pulse oximeter in its EvieMED Ring on 2 December 2024, for use in clinical trials, post-trial management and remote patient monitoring (AASM). That is a clinical channel, not a consumer purchase.
• Wrist devices: Apple lists a “second-generation electrical heart sensor” with the ECG app for ages 22 and over, plus irregular rhythm notifications; Samsung lists ECG and Irregular Heart Rhythm Notification. Both are long-established features on their platforms.

The takeaway is not that Circular is misleading anyone - its own wording is careful. It is that “has an ECG” and “has a regulator-reviewed ECG” are different claims, and on a ring you can buy today only the first one is established.

How we ranked them

Every pick carries its score from our published rubric: three-year cost of ownership (30%), evidence of accuracy (25%), claimed battery (15%), sizing and fit (10%), data ownership (10%) and phone support (10%), all set out on our methodology page. Nothing here was tested by us; every pick is Researched.

The order on this page is not score order, and the reason is the page's question. You asked for an ECG on a ring, so the ring with an ECG leads even though its evidence score is the lowest here and the RingConn Gen 2 scores highest of the four. We would rather rank by your question and show you the scores than quietly re-weight the rubric.

The picks in context

1. Circular Ring 2 — the only ring with an ECG

Worth respecting as engineering: a usable single-lead ECG in a titanium band a few millimeters thick, with a PDF export for a doctor's appointment, is a genuine first. Circular charges no forced subscription - “Nothing you need to see your own health is behind one” - claims eight days of battery in power mode and four to five in performance mode, offers haptic alarms, and ships worldwide with 14-day returns.

The caveats are real and we score them: no published validation of this ring exists, it is sold from Circular's own store rather than Amazon so our link earns nothing, sizes run “approximately half a size larger than standard ring sizing,” and some future features are unlocked with paid Circular Coins. Our Circular Ring 2 review goes through all of it, and Circular vs Oura puts it against the most-studied ring.

2. Apple Watch Series 12 — if you want a cleared heart feature today

Not a ring, and the honest answer for a reader whose real question is “I want my heart rhythm checked.” Apple lists a second-generation electrical heart sensor with the ECG app for ages 22 and over, irregular rhythm notifications, high and low heart rate notifications, hypertension notifications and sleep apnea notifications - none of it behind a subscription (Apple).

The costs: iPhone 11 or later on iOS 27 or later, up to 24 hours of battery, and a watch on your wrist. If you are weighing it against a ring for everything else, Oura vs Apple Watch is the page.

3. Samsung Galaxy Watch8 — the Android equivalent

Samsung Health is free, and the Watch8 lists ECG, Irregular Heart Rhythm Notification, personalised heart rate zones and sleep apnea risk detection. It needs Android 11.0 or above and a Samsung account, and some features are gated to a Galaxy phone rather than to a fee. Up to 30 hours in Always On Display mode, so it charges most days. Samsung's own ring, by contrast, has no ECG at all - see the Galaxy Ring review.

4. RingConn Gen 2 — the ring to buy if the ECG is a nice-to-have

Included because for many readers it is the right answer. No ECG, but no fee ever, 10-12 days a charge by RingConn's figure plus a case rated at up to 150 days, sizes 6-14 with a free kit, sleep apnea monitoring, and the only no-fee ring with a published chest-strap comparison: a 2026 preprint found a heart rate bias of -0.42 bpm against a Polar H10 in seated athletes (Tao et al.). It scores highest of the four here. See the RingConn Gen 2 review.

Side by side

What's coming, and what that's worth

Circular has announced a Ring 3 line with the FDA clearance claim above, haptics and contactless payments, but the dates are the whole story: pre-orders open in December 2026, pricing is unannounced, and first deliveries are “dates to be confirmed.” Nothing about that is unusual for this category; it just means the ring with a cleared ECG is not a thing you can order today.

Our standing advice on announced-but-unshipped hardware: buy what exists, or wait without paying. A pre-order is a loan to a company, and in this specific category rings have been delayed, redesigned and blocked by patent litigation - the history is in what the cheap listings really are and in our Ultrahuman review, where a ring left the US market entirely.

Who should buy which

• You want an ECG and it must be on a ring: the Circular Ring 2. Go in knowing it is unvalidated and bought direct.
• You want your rhythm checked and do not care about the form: the Apple Watch on an iPhone, the Galaxy Watch8 on Android. Both features are free and long-established.
• Your real worry is overnight breathing: different feature, different page - our sleep apnea guide covers which devices screen for it.
• You want the best ring, full stop: the RingConn Gen 2, and read our overall ranking.
• You have symptoms: a clinician. No consumer device on this page is diagnostic, and all three makers say so themselves.

Mistakes to avoid

• Assuming “has an ECG” means “FDA-cleared.” On rings you can buy today, it does not. Check the maker's own page, not a roundup.
• Reading a normal single-lead ECG as reassurance. AFib comes and goes. A clean reading is a clean reading of those 40 seconds.
• Buying a cheap ring that advertises ECG. The unbranded listings claim everything and verify nothing - our under $100 page lists the five things you cannot check.
• Ordering Circular in your normal ring size. Circular says its sizes run about half a size large. Use its sizing kit or printable guide.
• Paying for a ring you cannot return easily. Circular offers 14-day returns from its own store; check the window before you order, especially on a ring bought direct rather than through a marketplace.