The best smart rings, whether or not you'll pay a monthly fee

What a health tracking ring actually measures

A smart ring, sold under names like fitness tracker ring and health tracking ring, is a small set of sensors in a titanium band that reads your finger around the clock and hands the results to a phone app. Oura's Ring 5 page spells out the hardware most rings share: red and infrared LEDs for blood oxygen, green and infrared LEDs for heart rate, HRV and respiration, a digital sensor for temperature trends, and an accelerometer for movement (Oura). What each brand builds on top of those readings differs. Samsung rolls sleep, heart rate and activity into an Energy Score. RingConn Gen 3 adds blood pressure trend insights and sleep apnea pattern insights. Circular lists single-lead ECG and AFib detection.

The published evidence is strongest where a ring spends its most useful hours: overnight, with your hand still. Resting heart rate, HRV and sleep all have peer-reviewed studies behind them, at least for Oura. Workouts are the weak spot. DC Rainmaker found Oura Ring 5's workout heart rate “largely pretty good” against a Polar H10 chest strap on indoor rides and road runs, then saw it fall apart on a trail descent. Gadgets & Wearables found the RingConn Gen 2 read high against a chest strap on runs. If you train by heart rate zones, keep a strap for that job, and read how accurate smart ring heart rate really is before you hand a ring that work.

Best if you'll pay, best if you won't

A single winner hides the biggest decision in this category. We think the fee is the first fork in the road, so this list names a pick on each side of it.

• If you won't pay a fee: RingConn Gen 2. Everything in its app is included, it claims 10-12 days a charge, and its charging case stretches that to up to 150 days by RingConn's figure. The newer Gen 3 is the pick if you need a size 15 or want RingConn's longest single charge; the Gen 2 Air is the lower-cost way in.
• If you'll pay a fee: Oura Ring 4. It's the model a peer-reviewed study put against a chest strap for 536 nights, it comes in sizes 4-15, and it works on iPhone and Android. You'll pay Oura's membership, $5.99 a month or $69.99 a year, for as long as you want more than three daily scores.
• If you carry a Samsung Galaxy phone: Galaxy Ring. No fee and a charging case in the box, but some features, including Energy Score insights, need a Samsung Galaxy AI phone, and it doesn't work with iPhone at all.

If you've already decided you won't pay, our ranking of the best smart rings without a subscription goes deeper on the no-fee side alone. This page covers the whole market, Oura included, so you can see what the fee buys before you rule it out.

What each ring costs to own

Here's every ring on this list with the fee it requires over one, three and five years. Hardware prices move daily, so we link to the live price instead of printing one. Your total is the ring price plus the fee column.

For the fine print brand by brand, what a smart ring really costs over three years lays out every policy, and what Oura's membership costs covers exactly what the fee unlocks and what you keep without it.

How we ranked the whole market

Every ring is scored on the same published rubric: cost of ownership over three years (30%), evidence of accuracy (25%), claimed battery (15%), sizing and fit (10%), data ownership (10%) and phone support (10%). The weights and the reasoning behind each score are on our methodology page. We haven't worn or lab-tested any of these rings. Scores come from brand fee, spec, sizing and warranty pages and from named studies, all linked in the sources below.

We break our own score order once, on purpose. The Oura Ring 4 scores 6.0 overall because its fee drags cost of ownership down to 3 out of 10, yet it scores 9 on evidence, the highest of any ring here. On a no-fee list that fee rules it out. On a whole-market list, where some readers have decided the membership is worth it, we rank it third so those readers find the best-evidenced option without scrolling past five rings they've already ruled out. The Oura Ring 5 ranks last: the same fee, a narrower size range and no published validation of its own yet.

Two rings aren't here. We couldn't confirm the Amazfit Helio Ring is still sold in the US (Amazfit's US store pages returned 404 when we checked), and Ultrahuman's Ring AIR isn't sold to US buyers.

Battery, sizes and phones side by side

Two things stand out. Only the Galaxy Ring is Android-only, and only three rings go up to a size 15: RingConn Gen 3, Galaxy Ring and Oura Ring 4. Sizes aren't interchangeable between brands, so a 10 in one isn't necessarily a 10 in another; our smart ring sizing comparison explains why no official conversion exists. For every published spec in one place, including warranty and HSA/FSA status, see the smart ring comparison chart.

The picks in context

1. RingConn Gen 2: best smart ring overall

The Gen 2 wins the whole market for the reason it wins the no-fee list: sleep, heart rate, HRV and activity with nothing to pay after checkout, and a charging routine you barely notice. RingConn claims 10-12 days per charge and up to 150 days with the included case. It supports iOS 17 and Android 10 or newer and comes in sizes 6-14 with a free sizing kit. Its evidence is thin but real: a 2026 preprint (Tao et al., not peer-reviewed) compared it with a Polar H10 in 64 seated athletes and found a heart rate bias of -0.42 bpm. That says nothing about workouts, where Gadgets & Wearables saw it read high, or about sleep staging, and its “90.7% Sleep Apnea Monitoring Accuracy” is RingConn's own claim. Full detail in our RingConn Gen 2 review.

2. RingConn Gen 3: the newest RingConn, sized to 15

Gen 3 takes the Gen 2 formula and stretches it. RingConn rates it at 11-14 days per charge and 150+ days in total with its charging case, sells it in ten sizes from 6 to 15, and rates it IP68 and 10ATM. The Gadgeteer lists it at 2.3 mm at its thinnest and got about 10 days a charge with vibration alerts switched on. New features include Vascular Health Insights, which combines “nighttime vascular load patterns, optional manual blood pressure inputs, and lifestyle factors” into blood pressure trend insights, and Sleep Apnea Pattern Insights. RingConn is clear that Gen 3 is “not a medical device.” It sits second only because no study has tested Gen 3 itself, and it showed “Out of stock” on RingConn's own store when we checked, though Amazon listed it. Compare the two in RingConn Gen 3 vs Gen 2 or read the RingConn Gen 3 review.

3. Oura Ring 4: best if you'll pay a membership

If the fee doesn't bother you and evidence is what you're buying, this is the ring. Dial et al. (Physiological Reports, 2025) tested Oura Gen 3 and Gen 4 against a Polar H10 across 536 nights in 13 adults and found the Oura rings agreed most closely of every wearable tested: Gen 4's resting heart rate error was 1.94% and its HRV error 5.96%. The study was funded by the US Air Force Research Laboratory, and the authors declared no competing interests. It was also small, covered nighttime readings only, and the5krunner noted accuracy dropped at very high HRV. Ring 4 comes in sizes 4-15, the widest range Oura sells, and Oura rates it at typically 5-8 days. The costs: the membership, a battery excluded from Oura's one-year warranty, and a question mark over availability. It's no longer on Oura's own ring list, though Amazon still lists it and Gizmodo reported clearance pricing after Ring 5 launched. Android Authority also reported that Oura's pre-IPO filing tied a jump in warranty expenses to Ring 4 battery problems. Our Oura Ring 4 review weighs it up.

4. RingConn Gen 2 Air: the lower-cost no-fee pick

RingConn lists the Air below Gen 2 and Gen 3 on its own store, and it gives up what you'd expect. There's no charging case, no sleep apnea monitoring (RingConn says the Air “does not include sleep apnea monitoring”), and a titanium steel shell with PVD coating instead of Gen 2's titanium alloy. You keep the no-fee app, up to 10 days per charge with 90-minute fast charging, the same 6-14 sizes as Gen 2, and iOS 17 and Android 10 support. No study has tested the Air. For a first ring on a tighter budget it covers the core job; see the best budget smart rings and our RingConn Gen 2 Air review.

5. Ultrahuman Ring PRO: longest claimed battery, if you can wait

On paper the PRO outlasts everything here: up to 15 days a charge and up to 45 days with the PRO Charging Case that comes in the box. It comes in sizes 5-14 with a free sizing kit, has a titanium unibody rated to 100 meters, and uses what Ultrahuman calls ProRelease Technology, which “enables Ring PRO to be cut apart more easily in the event of swelling or injury to the finger.” No fee is required. The problems are getting one and trusting it. It's a US pre-order from Ultrahuman's own store (“ships October 10th onwards” when we checked, after earlier dates slipped), it isn't sold on Amazon.com, Ultrahuman doesn't state its phone requirements on the US pages we checked, and its only published data is an in-house pilot on the older Ring AIR. The Ultrahuman Ring PRO review covers the import ban that pulled the AIR from the US.

6. Samsung Galaxy Ring: best for Samsung phone owners

No fee, a charging case in the box (up to 14 days total, per Samsung), sizes 5-15, a titanium frame, and 10ATM plus IP68 ratings. On a Samsung Galaxy phone it's a complete package. Anywhere else it shrinks: no iPhone support, Double Pinch and Find My Ring don't work on other Android brands, and Energy Score insights need a Samsung Galaxy AI phone. Samsung rates sizes 12-13 at up to 7 days and smaller sizes at up to 6; GSMArena got about 5 from a size 11. We found no peer-reviewed validation of it. Samsung has announced an FDA-cleared sleep apnea risk feature for the ring this fall, which could change its standing once it's live. See the Galaxy Ring review and the best smart ring for Android.

7. Circular Ring 2: ECG on the spec sheet, bought direct

The only ring here that lists single-lead ECG and AFib detection, with Circular's own caveat that it's “not a diagnostic device and does not replace medical advice.” It works with iOS 15 and later and Android 9 and later, claims 8 days in power mode or 5 in performance mode, and carries a one-year US warranty and 14-day returns. It ranks low because we found no published validation of it, it's sold only on Circular's store, some future features cost Circular Coins, and it runs about half a size large by Circular's own sizing note. More in our Circular Ring 2 review.

8. Oura Ring 5: the current Oura, with the same fee

Oura's newest ring, announced May 28, 2026, has what TechCrunch called a thinner, lighter design (“from 2 grams” depending on size). It claims 6-9 days a charge “depending on ring size and usage” and lists heart rate, HRV, blood oxygen, temperature trends, Symptom Radar, Cardiovascular Age, Blood Pressure Signals and Cycle Insights. DC Rainmaker got 6-7 days in real use and saw “no meaningful difference between Oura and other wearables for core sleep stats.” It ranks last here for three reasons: the same membership as Ring 4, sizes only 6-13, and no published validation of Ring 5 itself yet. If you're choosing between Oura generations, Oura Ring 4 vs 5 lays out the trade, and the Oura Ring 5 review covers what the membership unlocks.

What the evidence says, brand by brand

Accuracy is where the market is most lopsided. Here's what we found published for each brand, and who paid for it.

• Oura: the deepest record by far. Beyond Dial et al., Cao et al. (JMIR, 2022) found Oura “could accurately measure nocturnal HR and RMSSD” against a chest ECG in 35 healthy adults, and Liang et al. (Sensors, 2024) found strong agreement overall but higher HRV error in older adults. One widely cited sleep study, Robbins et al. 2024, was funded by Oura.
• RingConn: one preprint on Gen 2 (Tao et al., 2026), not peer-reviewed, in seated athletes at rest.
• Ultrahuman: an in-house pilot on the Ring AIR (6 volunteers, 36 sleeps), not peer-reviewed, with all authors from Ultrahuman. the5krunner on the Ring PRO: “Independent testing will be the key test - watch this space.”
• Samsung: no peer-reviewed validation of the Galaxy Ring found.
• Circular: none found. A 2025 sleep-lab study tested a ring called “Circul,” which is a different product.

The no-fee rings aren't proven inaccurate; they're unproven. You can close part of that gap yourself: testing your ring against a chest strap takes about a week, and how accurate smart rings are covers every study we found. For sleep specifically, see the best smart ring for sleep tracking.

If this is your first smart ring

Beginners usually ask which ring is best, when the more useful first question is which ring fits your life. Four decisions settle most of it, in this order:

1. Fee or no fee. Decide before you fall for a feature. If a recurring bill for your own data is a dealbreaker, Oura is out and the rest of the market is open.
2. Your phone. iPhone owners can skip the Galaxy Ring. Samsung Galaxy owners get the most from it. Everyone else is choosing between RingConn, Oura, Ultrahuman and Circular.
3. Your size, measured with the brand's own kit. Every brand here says its sizing differs from standard rings, and Oura says its sizing differs even between its own generations. Our smart ring sizing guide walks through it.
4. Your finger. Oura recommends the index finger for best accuracy; our guide to which finger to wear a smart ring on covers the other brands.

After that, the differences between the top picks come down to battery, evidence and a handful of features, which the tables above lay out.

What to check before you buy

• Where it's sold. RingConn, Oura and Galaxy Ring are listed on Amazon.com. Ultrahuman Ring PRO and Circular Ring 2 are brand-store only, so their own terms apply (Circular offers 14-day returns).
• The warranty on the battery. Every brand here offers one year in the US. Oura excludes batteries as consumables; RingConn excludes normal battery capacity loss but sells optional two- and three-year protection in the US. Our warranty and returns guide compares them.
• HSA/FSA. Oura, RingConn (through Flex), Ultrahuman (with Flex), Samsung and Circular describe their rings as HSA/FSA eligible. IRS rules exclude expenses “merely beneficial to general health,” and Flex routes purchases through a clinician consult that may issue a Letter of Medical Necessity if you have a qualifying condition. Check with your plan administrator; our guide to smart ring HSA/FSA eligibility explains.
• Stock. RingConn's own store showed Gen 3 out of stock when we checked, while Amazon listed it. Ultrahuman's ship date has moved more than once.

Common mistakes

• Buying Ring 5 in your Ring 4 size. Oura says Ring 5's “redesigned interior fits differently than Oura Ring 4.” Re-size with the new kit.
• Assuming “no subscription” means no paid extras. Ultrahuman and Circular sell optional ones; RingConn doesn't.
• Taking battery claims at face value. They're maker figures under maker conditions. Our smart ring battery life guide reads each one with its fine print.
• Buying a ring to coach your workouts. Reviewers found ring heart rate unreliable on runs and trail descents. A ring is a sleep and recovery tool first.