A health-tracking ring is bought in a fixed order: first the phone it must pair with, then the plan its app needs, then the size it must fit, and only then the battery, water and sensor claims. Settle those in that order and confirm the exact US package, because a ring family can hide different finishes, sizes, chargers and paid add-ons under one product page.
Start with your phone
Every ring here depends on a phone app, and the makers do not support the same phones. Samsung states that the Galaxy Ring must be paired with a smartphone running Android 11.0 or above with at least 1.5 GB of memory, the Galaxy Wearable and Samsung Health apps and a Samsung account, and its current US buy page names Samsung Galaxy smartphones; features such as Energy Score need a compatible Galaxy phone. Oura, RingConn, Ultrahuman and Circular state both iOS and Android apps. Only RingConn publishes minimum versions for the Gen 2: iOS 17.0 and Android 10.0. Where two official pages describe compatibility differently, as Samsung's do, treat support on other phones as unconfirmed and ask the maker.
Read what the app shows without a paid plan
Subscription terms decide what you see after the first month, so read the maker's exact words. Oura states that without an active Oura Membership the app shows only the Readiness, Activity and Sleep scores, ring battery, basic profile, settings and Explore content; new members receive one included month, and plans renew automatically. Samsung's launch release states that Galaxy Ring data and insights come without a subscription, although its Galaxy AI footnote only promised free AI features until the end of 2025. RingConn lists its subscription fee as free. Ultrahuman includes core features but sells premium PowerPlugs and an optional plan, and Circular unlocks a few premium screens with coins earned by wearing the ring. This catalogue records no prices, and a trial month is not a permanent entitlement.
Size the ring before you pay
Smart ring sizes are not jewelry sizes, and they can change between generations of the same brand. Each maker here offers its own sizing kit: Oura recommends wearing its sizer for 24 hours, Samsung ships a kit first when you order without a size, and RingConn, Ultrahuman and Circular offer a kit as a separate order route. The packages recorded here are the route where the buyer already knows the size, so the kit is not in the box. Sizes run 4 to 15 for Oura Ring 4, 5 to 15 for Galaxy Ring, 6 to 14 for RingConn Gen 2 and Circular Ring 2, and 5 to 14 for Ultrahuman Ring PRO.
Compare battery claims by size and setting
Battery figures are manufacturer estimates, and most depend on ring size because smaller rings hold smaller batteries. Oura states 5 to 8 days from tests on sizes 8 to 10 with Blood Oxygen Sensing off and says that feature can cut up to two days. Samsung states up to 6 days for sizes 5 to 11 and up to 7 days for sizes 12 to 15. RingConn states 10 to 12 days across its size groups, Ultrahuman about 12 days in Turbo Mode and more than 15 in Chill Mode, and Circular about 8 days in power mode. Days quoted with a charging case, such as Samsung's 14 days or Ultrahuman's 45 days, count recharges from a case battery and are not ring figures. Weight also changes with size: Oura states 3.3 to 5.2 g and Ultrahuman 3.3 to 4.8 g, while Circular gives a single 4 g figure without a size basis.
Read the water rating in the maker's terms
Water ratings are not interchangeable. Samsung describes the Galaxy Ring as consistent with 10ATM, up to 100 m of water for up to 10 minutes, and IP68, up to 6 feet for up to 30 minutes. Oura and Ultrahuman state water resistance to 100 m, and Oura advises against scuba diving. RingConn states IP68 with 100 m, and Circular states IP68 with no depth or duration. A 100 m figure is not a diving rating; follow each maker's stated limits for submersion, heat and diving.
Match the sensors and the health wording
Listed sensors tell you what the ring can sense, not how accurate a metric is. Oura lists red, infrared and green LEDs, a temperature sensor and an accelerometer; Samsung an accelerometer, optical sensor and skin temperature sensor; Ultrahuman temperature, PPG and a 6-axis IMU; and Circular adds an ECG sensor. RingConn's Gen 2 page lists no sensor hardware. These are wellness products unless a maker states a clearance: Samsung says the Galaxy Ring is for general wellness and fitness only, Ultrahuman says Ring PRO is not classified as a medical device, and Circular calls its blood pressure reading a wellness estimate, not a diagnosis, while stating no clearance for its ECG or AFib features. RingConn's sleep apnea accuracy figure is its own claim. None of these readings replaces a clinician.
Confirm the package
Match the seller's finish, size and model code to the maker's page. Samsung's US page data gives a model code per size and finish, such as SM-Q508NZKAXAR for a size 8 Titanium Black ring; the other makers publish no part number on the pages read. The box normally holds the ring, its charger or case and a USB-C cable. A spare case, sizing kit, extended protection plan or paid app plan is a separate purchase unless the package lists it.
Common questions
Is a free first month of membership the same as no subscription?
No. An included month is a trial. Oura states that after it the membership renews automatically, and without an active membership the app shows only three daily scores and a few basic screens.
Can I compare battery life between ring sizes?
Only roughly. Makers state that smaller rings hold smaller batteries and test under their own settings, so read the size basis and the features that were switched off before comparing two figures.
Does a ring with ECG or sleep apnea features diagnose a condition?
Not unless the manufacturer states a regulatory clearance for that feature. The makers recorded here describe their rings as wellness products or state no clearance, so discuss any reading with a clinician.
Sources & further reading
- Oura Membership support articleChecked 2026-10-21
Support article updated 16 October 2026 used for what membership includes, the one included month for new members, automatic renewal and exactly what remains visible without an active membership. Prices are not recorded.
- Oura Ring 4 battery life support articleChecked 2026-10-21
Support article updated 21 September 2026 giving the test basis for 5 to 8 days: sizes 8 to 10, Blood Oxygen Sensing disabled, one hour of activity heart rate and eight hours of sleep per day, and the effect of ring size and settings.
- Samsung US Newsroom Galaxy Ring launch release and specificationsChecked 2026-10-21
July 2024 Samsung Electronics America release used for weight by size 5 to 13, 7.0 mm x 2.6 mm, the Android 11.0 and 1.5 GB phone requirement, the required apps and account, the statement that insights come without a subscription, the general wellness wording and the box contents. Its Galaxy AI footnote promised free features only until the end of 2025.
- How to charge the Galaxy RingChecked 2026-10-21
Samsung US support answer used for the charging case with its own battery and USB-C cable, wireless and Wireless PowerShare charging, 1.6 ring charges per full case and the rated battery capacity and battery life by size, including sizes 14 and 15.
- RingConn Gen 2 product pageChecked 2026-10-21
Manufacturer store page with US pricing, used for the finishes, sizes 6 to 14, the free sizing kit route, battery life by size, specifications, phone compatibility, the no-subscription statement, the sleep apnea monitoring claim and the box list. Sensor hardware is not listed on this page. Price and stock were not recorded.
- Ultrahuman Ring PRO FAQChecked 2026-10-21
Manufacturer FAQ used for battery modes, sensors, the metrics they cover, weight by size, the cut zone, the subscription answer, the box contents, the one-year warranty and the statement that Ring PRO is not classified as a medical device.
- Ultrahuman PowerPlugsChecked 2026-10-21
Manufacturer page listing free and premium PowerPlugs and stating that AFib Detection is available in Europe, the UK, Turkey, Switzerland and more, with a USA launch still planned. Prices on the page are not recorded.
- Circular Ring 2 store pageChecked 2026-10-21
Manufacturer store page in US dollars with worldwide shipping, used for finishes, sizes US 6 to 14, the replica-ring sizing kit option, specifications, sensors, iOS and Android compatibility, the subscription FAQ, the ECG and blood pressure wording and the box list. No FDA or other regulatory clearance is stated on the page. Price and stock were not recorded.
See our methodology for source labels and limitations. Product evidence dates are shown beside the corresponding specifications.
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