Smart ring

Circular Ring 2

Name: Circular Ring 2
Brand: Circular
Price: 349.00 USD

Smart ring with on-demand ECG, a charging case and no mandatory subscription

$349US price, checked Oct 24, 2026

Check price at Circular

By Porsche Ma Price checked Oct 24, 2026

Our reviews rest on published sources, not hands-on testing. Our method

Porsche also cofounded Superhuman Chambers, which sells hyperbaric chambers · About the author. This is general information, not medical advice, and no clinician has reviewed it.

The verdict

Circular Ring 2 is a $349 titanium smart ring with a single-lead ECG, a charging case and no mandatory subscription. Circular says its AFib classification uses an FDA-cleared algorithm, but it also says the ring isn't a medical device. Its blood pressure estimate comes with no published accuracy data.

The trade-off

Circular publishes no accuracy data for its blood pressure estimate and names no maker for its FDA-cleared algorithm.

At a glanceSmart ring

Battery and charging: About 8 days in power mode and about 5 days in performance mode…
Sensors: Single-lead ECG, optical PPG (green, red and infrared)…
ECG and AFib: Circular says the AFib classification uses an algorithm cleared by the FDA
Blood pressure estimate: Circular estimates blood pressure from the pulse wave timed between…

All the details →

Model reviewed: Obsidian Black finish, US sizes 6 to 14 (or the $5 sizing kit option), charging case included

$349

US price, checked Oct 24, 2026

Check price at Circular

No affiliate commission on this link. Check the exact variant before buying.

Returns 14 days from receipt, for any reason, if the ring is unused and in its original condition. See conditions
Warranty One year from delivery, covering defects in materials and workmanship (two years in the EU under local law). See conditions
Delivery Ships to the US with import duties and taxes prepaid (Delivered Duty Paid.

About this price

Circular's US store listed Obsidian Black at $349 in every size from 6 to 14. The listing showed no higher regular price, so this is the regular price and not a sale. The store's cart reports US dollars. Silver was $449, and Rose Gold and Gold were $549. Picking the sizing-kit option instead of a size adds $5. Circular's terms say shipping and handling are included in a ring's price. They also say import duties and taxes are prepaid for US deliveries. The price is before any sales tax. It leaves out the optional Circular+ Guarantee add-on ($20 billed yearly). It also leaves out the paid parts of some app features.

Where $349 sits among the 17 wearable prices we checked

$200$400

Related comparisons: Oura Ring 5 vs WHOOP Peak vs Ultrahuman Ring PRO

Running costs: WHOOP membership cost and is it worth it? Wearables over 3 years

A GOOD FIT FOR

You wear a US size 6 to 14 and want an on-demand ECG from a ring for $349 without a required yearly plan.

You want an on-demand single-lead ECG from a ring and would rather not pay a required yearly plan
You want sleep, HRV and temperature trends and are comfortable with accuracy claims that come from Circular itself
You wear a US size 6 to 14 and use Apple Health or Android Health Connect
You'd rather pay $349 once and accept a one-year warranty

THINK TWICE IF

Anyone who wants a medical device, since Circular says the ring isn't one
Anyone who needs blood pressure numbers they can rely on, since Circular calls them wellness estimates and publishes no accuracy data
Anyone who may change their mind after wearing it, since returns need an unused ring and Circular keeps $25 of the refund
Anyone who wants a replaceable battery, since Circular says the battery can't be replaced
Anyone who wants the newest model, since Circular Ring 3 pre-orders open in January 2027

What still needs checking

Which company makes the FDA-cleared AFib algorithm, and its 510(k) number
Independent accuracy data for Ring 2's ECG, sleep, blood oxygen and blood pressure, since Circular's own validation work is still in review
What the Circular+ Guarantee covers and what a Circular+ subscription costs
Whether the advanced parts of blood pressure are paid for every buyer, since the pages disagree
Whether Oura's license names Ring 2, how long it lasts and what the royalty is
Battery lifespan, out-of-warranty replacement cost and charger power draw
Inner diameter for each size and the minimum iOS and Android versions
The ring's FCC equipment authorization, which the pages checked don't mention
How long Circular will keep selling and supporting Ring 2 after Ring 3 launches

The practical details.

Specifications for Circular Ring 2
Exact variant	Obsidian Black finish, US sizes 6 to 14 (or the $5 sizing kit option), charging case included
Battery and charging	About 8 days in power mode and about 5 days in performance mode per the spec table (the FAQ says 4 to 5). The wireless case recharges the ring in about 30 minutes. A case is included.
Sensors	Single-lead ECG, optical PPG (green, red and infrared), skin temperature and a 3-axis accelerometer. Circular's science page lists the ECG at 510 Hz and the optical signal at 25 Hz.
ECG and AFib	Circular says the AFib classification uses an algorithm cleared by the FDA. It names no algorithm maker or clearance number on the pages checked. You can export the trace as a PDF.
Blood pressure estimate	Circular estimates blood pressure from the pulse wave timed between its ECG and optical sensors. You enter three cuff readings at setup and one every 30 days. A session takes about a minute and lands in one of six bands. Circular calls it a wellness estimate, not a diagnosis, and publishes no accuracy data.
Subscription and paid features	Circular says no subscription is mandatory, and the product page says blood pressure comes included with nothing to renew. Its help center says the advanced parts of blood pressure and glucose are paid, by card or with app coins. Those parts are insights, long-term trends and PDF export. The Circular+ Guarantee add-on is $20 billed yearly.
Sizes and fit	US 6 to 14, no half sizes. Sizes run about half a size above standard. A sizing kit is a $5 size option and can't be returned.
Water resistance and storage	IP68, and Circular's FAQ says showers and swimming are fine. The ring stores 7 days of data and then overwrites the oldest. Circular suggests syncing every 5 to 6 days.
Compatibility	iOS and Android over Bluetooth Low Energy. It syncs with Apple Health and Android Health Connect. Circular lists no minimum iOS or Android version on the pages checked.
Delivery	Ships to the US with import duties and taxes prepaid (Delivered Duty Paid, per Circular's terms). Estimated delivery runs 3 to 25 days depending on method and address. Shipping and handling are included in a ring's price.
US import status	Circular SAS was named in Oura's ITC case 337-TA-1398. It settled with Oura in June 2024, and the ITC ended the case against it in 2024 on that settlement. The August 2025 exclusion order covers the remaining respondents, and the cease and desist orders went only to Ultrahuman and RingConn. Oura says Circular holds a multi-year license, subject to royalties. Oura's newer ITC case, 337-TA-1468, doesn't name Circular.
Next model	Circular Ring 3 comes as a Pro and a Slim. Circular says pre-orders open in January 2027 and prices come at launch. It says Ring 2 stays on sale until Ring 3 is released.
Dimensions	Circular's product page lists the ring as 2.55 mm thick, 7.8 mm wide and about 4 g. Its science page gives 4.5 g and a 2.6 mm profile, so the figures differ by page. Circular doesn't state weight or inner diameter for each size.
Materials	The product page says titanium with a PVD finish and a hypoallergenic inside. Circular's science page describes grade-5 titanium with a diamond-like carbon coating instead. Circular doesn't name the inner material.

Before you buy

InstallationNo installation

No installation. You pair the ring with the Circular app on iOS or Android over Bluetooth Low Energy. The box holds the ring, a wireless charging case, a USB-C cable and a cleaning cloth. Circular sizes run about half a size above standard ring sizes, so a standard 9 means a Circular 10. If you don't know your size, a sizing kit costs $5 as a size option. A size exchange has to happen within 14 days of delivery.

WarrantyOne year from delivery, covering defects in materials…

One year from delivery, covering defects in materials and workmanship (two years in the EU under local law). It excludes a wrong size, normal wear and tear, cosmetic damage such as scratches, accidents and misuse. Batteries are covered only if a defect damaged the product. Circular's help center says the battery can't be replaced and offers a discount code toward a new ring if it weakens. The optional Circular+ Guarantee costs $20 billed yearly, and the product page describes it only as extra protection.

Returns14 days from receipt, for any reason, if the ring is unused and in its original condition

14 days from receipt, for any reason, if the ring is unused and in its original condition. You email support with a photo and your order number to start the return. For a change-of-mind return you pay shipping back, and Circular keeps a fixed $25 of shipping and handling from the refund. Import taxes aren't refunded. Sizing kits can't be returned. A size or color exchange has its own 14-day window, and you pay the shipping.

More about this assessment

Circular Ring 2 is a titanium smart ring that costs $349 in Obsidian Black on Circular's US store. A wireless charging case comes in the box. Circular says no subscription is mandatory, rates the battery at about 8 days and ships to the US with import duties and taxes prepaid. It has a single-lead ECG, optical pulse, temperature and motion sensors. The catch is the health claims. Circular says its AFib classification uses an FDA-cleared algorithm. It also says the ring isn't a medical device, and it publishes no accuracy data for its blood pressure estimate. Circular says Ring 2 stays on sale until Ring 3 is released, and Ring 3 pre-orders open in January 2027.

Strengths on paper

No mandatory subscription, and the $349 price includes the charging case, shipping and US import duties
Single-lead ECG with PDF export, and an AFib classification that Circular says comes from an FDA-cleared algorithm
Battery rated at about 8 days in power mode, with a 30-minute recharge from the wireless case
Titanium ring with IP68 water resistance in US sizes 6 to 14
Syncs with Apple Health and Android Health Connect
14 days to return it or exchange the size

Limitations

Circular says the ring isn't a medical device, and its terms say the accuracy of the data isn't meant to match medical devices
Circular names no maker or clearance number for its FDA-cleared algorithm, and an openFDA search under Circular's name shows no ring or ECG record
Circular's blood pressure page says the ring meets a clinical accuracy standard, but it shows no data to back that up
Circular's pages disagree on blood pressure pricing: the product page says included, and the help center says the advanced parts are paid
Circular's features page marks its blood pressure trend as still in testing, while a banner on the product page says it's live
Circular's science page says published evidence doesn't support inferring blood pressure or glucose from optical data, and the ring's blood pressure estimate combines optical and ECG signals
Returns need an unused ring in original condition, you pay return shipping, and Circular keeps $25 of the refund
The warranty lasts one year, excludes battery wear and cosmetic damage, and the battery can't be replaced
Weight and thickness differ by page: about 4 g and 2.55 mm, or 4.5 g and 2.6 mm

Running costs.

PLAN YOUR OWNERSHIP COSTS

What will it cost to own?

Change the assumptions to fit your use. Leave an unknown cost blank. Add water, subscriptions, cleaning, shipping and taxes if they apply. Use average operating power, not the maximum rating.

Purchase price ($)Installation / accessories ($)Annual consumables ($)Average operating power (W)Hours per dayAnnual other costs ($)Electricity ($/kWh)Years

3-year known subtotal

$349.00

Incomplete: energy use. This is not the full ownership cost.

Energy component: Unknown

Purchase + installation + years × (annual consumables + annual other) + watts/1000 × hours/day × 365 × years × $/kWh. Annualized allowances, not an exact replacement schedule. Excludes taxes, shipping, finance and resale unless entered.

Replacement parts & cost assumptions

No scheduled consumable is listed. That doesn’t mean zero maintenance or repair costs.

Purchase is the $349 Obsidian Black price on Circular's US store. It includes the charging case, shipping and handling, and US import duties. Circular says no subscription is mandatory, so other yearly costs are $0 and three years comes to $349 before tax. Silver costs $100 more, and Rose Gold and Gold cost $200 more.
The estimate leaves out the optional Circular+ Guarantee ($20 billed yearly). It also leaves out the paid parts of some app features, which Circular says you can buy by card or with app coins. The pages checked give no price for a Circular+ subscription.
Circular says the battery can't be replaced, and the warranty excludes battery wear unless a defect caused it. A weak battery means a discount code toward a new ring, with no amount stated. Circular doesn't state the charger's power draw, so energy cost is unknown.

Evidence & sources.

How accurate are sleep trackers? Our evidence review grades the research as Moderate. That grade is about the claim, not about this product.

Manufacturer claimPrice, finishes, sizes, sensors, battery life, dimensions, materials, water resistance, box contents, compatibility, shipping, warranty and return terms all come from Circular's own pages.^{1–3, 6–8} Not independent testing. Circular's pages differ from one another on weight, thickness, battery days and ECG time, as the specifications note.
Manufacturer claimCircular says its AFib classification uses an algorithm cleared by the FDA. Its help center says Ring 2 is not classified as a medical device as a whole. It adds that the ring is not intended to diagnose, treat or cure any condition. Its terms of sale say the accuracy of the data isn't intended to match that of medical devices.^{1, 7, 9} This is Circular's own statement of its regulatory position. The pages checked name no algorithm maker or 510(k) number.
Regulator recordA search of the openFDA 510(k) database for applicants named Circular on Oct 24, 2026 returned one record. It was for a cervical and lumbar traction device from an unrelated company. No ring or ECG record came back.¹⁸ A clearance held by a supplier wouldn't appear under Circular's name, and Circular doesn't say which company holds it. The search shows no clearance in Circular's own name.
Manufacturer claimCircular's blood pressure page says the ring meets a standard of 5 mmHg mean error or less, with a standard deviation of no more than 8 mmHg. It shows no study or data. Its science page says published evidence doesn't support inferring blood pressure or glucose from optical data.^{4, 5} The science page lists Circular's own validation work as a sleep-staging preprint in review (312 nights) and an AFib paper under review (604 recordings). Neither covers blood pressure. No independent Ring 2 validation study was reviewed for this review.
Regulator recordThe ITC's August 2025 notice in Investigation No. 337-TA-1398 found a violation of Section 337. It issued a limited exclusion order, with cease and desist orders against Ultrahuman and RingConn. Circular SAS was named in the April 2024 notice of investigation. The Commission had ended the case against it on settlement (Order No. 12, July 9, 2024).¹⁵ The notice doesn't give the settlement's terms.
Manufacturer claimOura announced on June 25, 2024 that it had settled its patent litigation with Circular in a Texas federal court and at the ITC. Oura granted Circular a multi-year license to keep selling Circular smart rings and the app, subject to royalty payments. The terms are confidential.¹⁷ This is Oura's announcement. It doesn't name a Circular ring model.
Regulator recordOura's newer ITC complaint, instituted in December 2025 as Investigation No. 337-TA-1468, names Samsung, Reebok, Zepp Health and Nexxbase entities as respondents. It doesn't name Circular.¹⁶ The notice lists respondents as of institution. Later amendments aren't covered.