Smart rings comparison chart: all eight rings, fees included

How to read this chart

Every cell below comes from the brand's own spec, fee or warranty page, or from a named retailer listing or review, and each value links to the page it came from. We haven't worn or lab-tested these rings. The chart compiles what the makers publish, checked on September 19, 2026, so that one table can answer the questions a spec sheet usually buries. Four things to keep in mind as you read it:

• Battery figures are claims. Each brand measures under its own conditions, and several say the number depends on ring size and settings. Where a reviewer reported something different, we note it in the ring notes below. Our smart ring battery life guide reads every claim with its fine print.
• Sizes don't transfer between brands. No brand says its sizes match another brand's, and RingConn and Oura both say sizing differs even between their own generations. Our sizing comparison lays the ranges side by side.
• The score is ours. It weights three-year cost of ownership 30%, published evidence of accuracy 25%, claimed battery 15%, sizing and fit 10%, data ownership 10% and phone support 10%. It's an editorial judgment from published facts, not a test result, and the full rubric is on our methodology page.
• Ring prices aren't printed. They change daily, so every buy button links to the live price. Subscription fees are printed because brands publish them as policy.

The full chart

Rings are ordered by overall score, highest first. On a phone, scroll the table sideways.

A few patterns stand out once everything sits in one place. Oura is the only brand here that requires a paid plan for most of its insights, and that single fact explains why both Oura rings sit at the bottom of a list ranked on cost of ownership. Four rings ship with a charging case (RingConn Gen 2 and Gen 3, the Ultrahuman Ring PRO and the Galaxy Ring); neither Oura ring includes one, the Gen 2 Air doesn't, and Circular doesn't say. The Galaxy Ring is the only ring locked to one phone platform, and Ultrahuman is the only brand that doesn't publish its phone requirements. And two rings, the Ultrahuman Ring PRO and the Circular Ring 2, can't be bought on Amazon.com at all.

Three-year fees, every ring

A ring is a one-time purchase. A membership keeps billing as long as you wear the ring. This table multiplies each brand's required plan out over one, three and five years and links to the live ring price, so the total you'd actually pay is the ring price plus the fee column.

“No required fee” isn't quite the same as “nothing to buy.” Ultrahuman sells optional PowerPlugs (Cardio Adaptability at $24/year, Cycle & Ovulation Pro at $39/year) and optional UltrahumanX coverage from $36/year, and Tech Advisor reported that some future Circular features will cost paid “Circular Coins.” None is needed to see your core data. The whole picture, brand by brand, is in what a smart ring really costs over three years, and Oura's membership cost gets its own breakdown.

The row a chart can't show: evidence

A spec table can tell you how long a battery is claimed to last. It can't tell you how well the ring measures your heart rate while you sleep. That depends on published validation, and the gap between brands is wider than any spec row:

• Oura: the strongest by a distance. Dial et al. (Physiological Reports, 2025) compared Oura Gen 3 and Gen 4 with a Polar H10 chest strap over 536 nights in 13 adults; for Gen 4, resting heart rate error was 1.94% and HRV error 5.96% (Dial et al.). The study was funded by the US Air Force Research Laboratory, the authors declared no competing interests, and it covered nighttime resting data only. The Ring 5 itself hasn't been through the published studies yet.
• RingConn: a 2026 preprint (Tao et al., not peer-reviewed) compared the Gen 2 with a Polar H10 in 64 seated athletes and found a heart rate bias of -0.42 bpm (Research Square). We found nothing on Gen 3 or Gen 2 Air.
• Ultrahuman: an in-house pilot on the older Ring AIR (6 volunteers, 36 sleeps), written by Ultrahuman staff and not peer-reviewed. Nothing independent on the Ring PRO yet.
• Samsung: we found no peer-reviewed validation of the Galaxy Ring.
• Circular: none for the Circular Ring 2. A 2025 sleep-lab study tested a ring called “Circul,” which is a different product.

Our pillar on how accurate smart rings are walks through every study we found, including their funding and limits. If a gap on this list bothers you, you can close it yourself with a chest strap and a week of mornings; here's how to test your ring against a chest strap.

Notes on each ring

RingConn Gen 2 (8.2)

The highest-scoring ring in the chart and our pick for most people who refuse a fee. RingConn claims 10-12 days per charge and up to 150 days with the included case, and the Gen 2 is the only ring from a no-fee brand with a chest-strap comparison of its own. It needs iOS 17 or Android 10 or newer. The caveats: that comparison is a seated preprint, Gadgets & Wearables found the Gen 2 read heart rate higher than a chest strap on runs, and its “90.7% Sleep Apnea Monitoring Accuracy” is RingConn's own claim, not a diagnosis. Full detail in the RingConn Gen 2 review.

RingConn Gen 3 (8.1)

RingConn's newest ring and the longest single charge you can order on Amazon: up to 14 days (11-14 on RingConn's features page) and 150+ days in total with its Universal Charging Case. It also has the widest size range in the chart, 10 sizes from 6 to 15. The Gadgeteer's reviewer got about 10 days with vibration alerts on. It adds Vascular Health Insights, Sleep Apnea Pattern Insights and vibration alerts, and RingConn says it's “not a medical device.” It sits a tenth below Gen 2 only because we found no validation of Gen 3 itself. It showed “Out of stock” on RingConn's own store when we checked, though it was listed on Amazon. See the Gen 3 review and Gen 3 vs Gen 2.

RingConn Gen 2 Air (7.7)

RingConn lists the Air below Gen 2 and Gen 3 on its own store, which makes it the lowest-cost way into a no-fee ring here. You get up to 10 days per charge with 90-minute fast charging and the same 6-14 sizes as Gen 2. You give up the charging case, sleep apnea monitoring (RingConn says the Air “does not include sleep apnea monitoring”) and Gen 2's titanium alloy, which becomes titanium steel with a PVD coating. Our Gen 2 vs Gen 2 Air comparison and best budget smart rings cover the trade-offs.

Ultrahuman Ring PRO (6.9)

The longest claimed battery in the chart: up to 15 days a charge and up to 45 with the PRO Charging Case that comes in the box. Sizes run 5-14 with a free kit, and the titanium unibody is rated to 100 meters. It scores lower for practical reasons. 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 publish its phone requirements, and its only published data is an in-house pilot on the older Ring AIR. The Ring PRO review and RingConn vs Ultrahuman go deeper.

Samsung Galaxy Ring (6.2)

No fee, a charging case in the box (up to 14 days in total, per Samsung), sizes 5-15, titanium, and both 10ATM and IP68 ratings. It works only with Android 11 or newer, never iPhone, and on non-Samsung phones Double Pinch and Find My Ring don't work, while Energy Score insights need a Samsung Galaxy AI phone. Samsung claims up to 7 days for sizes 12-13 and up to 6 for smaller sizes; GSMArena got about 5 from a size 11. We found no peer-reviewed validation. Samsung has announced an FDA-cleared sleep apnea risk feature for the ring this fall, which wasn't live when we checked. See RingConn vs Galaxy Ring and the Galaxy Ring review.

Circular Ring 2 (6.0)

“No forced subscription,” single-lead ECG and AFib detection on its feature list, and phone support back to iOS 15 and Android 9. Circular says the ring “is not a diagnostic device.” Claimed battery is 8 days in power mode or 5 in performance mode. It runs about half a size large by Circular's own note, sells only from Circular's store with 14-day returns and a one-year US warranty, and we found no validation of this model. Read the Circular Ring 2 review or Circular Ring 2 vs Oura.

Oura Ring 4 (6.0)

The previous Oura and the most directly validated ring you can still buy: Oura Gen 4 is the model Dial et al. tested against a Polar H10. It also has Oura's widest size range (4-15). It claims 5-8 days a charge and carries the same membership as Ring 5. It has dropped off Oura's current ring list but is listed on Amazon, where Gizmodo reported clearance pricing after Ring 5 launched. Android Authority reported that Oura's pre-IPO filing showed a jump in warranty expenses in fiscal 2025 tied to Ring 4 battery problems. See Oura Ring 4 vs 5 and the Ring 4 review.

Oura Ring 5 (5.8)

Oura's current ring, announced May 28, 2026: 6-9 days per charge, sizes 6-13 (it fits differently from Ring 4), titanium inside and out, waterproof to 100 meters, iPhone and Android. It scores lowest here for one reason: without the membership, Oura says you see only three daily scores. Its evidence score is high by inheritance from Gen 3 and Gen 4. DC Rainmaker got 6-7 days from it and found workout heart rate against a chest strap “largely pretty good” on rides and road runs, but said it “basically falls apart” on a trail descent. No Oura feature is FDA-cleared. See Oura vs RingConn and the Oura Ring 5 review.

Rings not in the chart

We only chart rings a US buyer can order today. Three names that show up in other roundups didn't make it:

• Amazfit Helio Ring: we couldn't confirm it's still sold in the US. Amazfit's US product page returned a 404 when we checked, and its US store search showed no Helio Ring.
• Ultrahuman Ring AIR: not sold in the US since an International Trade Commission exclusion order in August 2025. The Ring PRO is its US replacement; Oura vs Ultrahuman explains what happened.
• Luna Ring: its maker, Nexxbase, agreed in an ITC consent order to stay out of the US market for the life of Oura's asserted patents, according to Oura.

Narrow it down in three questions

1. Will you pay a fee? If not, cross off both Oura rings. The ranked list for you is the best smart rings without a subscription.
2. Which phone do you carry? On an iPhone, cross off the Galaxy Ring, and check with Ultrahuman before pre-ordering a Ring PRO. On a Samsung Galaxy phone, the Galaxy Ring gets its full feature set. Our iPhone and Android rankings go from there.
3. Do you need it now, with Amazon's returns? Then cross off the Ultrahuman Ring PRO (a brand-store pre-order) and the Circular Ring 2 (brand store only).

Most buyers end up with two or three rings left, and that's where our head-to-heads come in: Oura vs RingConn, Oura vs RingConn vs Ultrahuman, Galaxy Ring vs Oura and the rest on the compare hub.