A ring that tells you your blood pressure sounds like the thing people have been waiting for. Circular started rolling exactly that out to every Ring 2 this month, on iOS and Android, in all markets. Before you read any headline about it, read one sentence from Circular’s help text: “It does not replace a cuff and it is not a diagnosis.” That honest frame comes from the company selling the ring.
Two app updates in September
Circular’s public release notes give two dates. App version 29.27.0, dated September 2, 2026, introduced the “Blood Pressure Circle: a new circle available now for compatible Gen 2 rings.” App version 29.28.6, dated September 13, 2026, added “a Blood Pressure calibration step: illustrated instructions for ring positioning”. It also fixed a bug that hid valid blood pressure results behind a recalibration prompt.
Eleven days after the feature arrived, Circular had to add illustrated instructions for positioning the ring. Placement matters more than a marketing page suggests.
Circular calls its ring the first smart ring to read blood pressure in seconds. It’s the company’s claim about its own place in the market, and we have no independent verification of it.
How the ring estimates pressure
The ring does not squeeze your arm, so it cannot measure pressure the way a cuff does. Instead, it builds a personal model.
Circular describes the setup this way: “Enter three readings from a validated cuff so the app can anchor the model to you, then take a reading from your finger in seconds. It shows where you sit against your own baseline and how the trend moves across days and weeks.”
You buy or borrow a proper upper-arm cuff, take three readings and type them in. From then on, the ring produces an estimate from optical sensor data mapped against those anchors. The ring has a 3-LED photoplethysmography sensor, plus a single-lead ECG, an accelerometer and a temperature sensor.
Getting the calibration right
Every reading you ever get is only as accurate as the three numbers you typed in at the start.
An unvalidated cuff, or one that is the wrong size for your arm, anchors the model to bad data. So do readings taken straight after coffee or a flight of stairs, or while you were sitting badly. The ring will still show confident-looking numbers afterward, and they will be consistently wrong.
Blood pressure also drifts over months with weight, medication, season and age, so an anchor set in September does not stay true forever. Circular’s September bug fix around recalibration prompts suggests that re-anchoring is a recurring part of owning the ring.
What the reading is good for
Treat the output as a direction and never as a diagnosis. The feature was designed that way.
A cuff answers “what is my blood pressure right now”. The ring answers “is my pressure trending above or below my own normal over recent weeks”, and that second question is useful. Rising blood pressure often has no symptoms, so it can go unnoticed until a routine appointment. A trend line that nudges you to book that appointment has real value.
The ring cannot stand in for a measurement where the exact number matters. Medication titration, a hypertensive episode, pregnancy monitoring and any reading your doctor will act on all need a cuff. Circular says so, and the app’s ECG carries a matching caveat: “the reading is designed to be shared with a clinician and is not a substitute for a diagnosis.”
Circular’s help center says the feature is not medically certified and that the company is “currently in the regulatory process with our partner for FDA clearance of the blood pressure estimation feature”. Until that clearance arrives, keep it out of anything clinical.
Glucose is next and deserves even more skepticism
Circular lists a “Glucose Circle” at 75 percent in its ongoing development notes and advertises a “non-invasive glucose trend estimate” as coming soon.
Non-invasive glucose sensing has defeated well-funded teams for two decades. A trend estimate is a softer claim than a measurement, and it may well be useful. It is also the category where careful wording hides how much is being promised. When it arrives, ask the same questions that apply today: what is it calibrated against, what does the company say it is not, and has anyone outside the company checked.
Price and what needs a subscription
In October 2026 Circular lists the Ring 2 at $349, in titanium. Returns are open for 14 days, and the manufacturer warranty runs one year (two years in the EU under local consumer law). In the United States, the ring is eligible for HSA and FSA spending. Phone requirements are iOS 15 or later and Android 9 or later. Water resistance is quoted at 50 m for up to 30 minutes.
On subscriptions, Circular puts it this way: “Nothing you need to see your own health is behind one. All essential core health tools and Kira, are included with the ring. A few Pro features can be unlocked in the app if you want them, always optional, never required.”
That is a real difference in this category. With the membership behind the Oura Ring 5 and its subscription, the monthly fee decides which insights stay visible. Both models can be defended, but only Circular’s lets you stop paying and keep reading your own data.
Battery and charging figures that disagree
Circular’s specification block for the Ring 2 says battery life is “up to 7 days”, with a charging case that takes “about 60 minutes”. The frequently asked questions on the same page say “up to eight days depending on how often you take ECG readings and run live measurements”. They also say “a full charge takes about ninety minutes on the dock”.
The gap between seven days and eight, or sixty minutes and ninety, is small, and the fix is obvious. But if battery life is why you’re choosing between rings, ask support which figure is current before you trust the larger one.
Should you buy a ring for this?
If you already own a Ring 2, update the app, borrow a validated cuff and take the three readings properly. Then use the results for what they are. Circular’s help center lists unlimited measurements and a daily view as free for every Ring 2 owner, so that part costs you nothing and the information has some value. Long-term trends and a PDF export of your history for your doctor are part of Premium.
Anyone buying specifically for blood pressure should get a validated upper-arm cuff first. It costs far less and gives you a real number, and the ring’s feature is worthless without one anyway. The ring is a reasonable buy if you want continuous sleep, recovery and ECG data with no mandatory subscription. The pressure trend is a bonus on top of that.
That changes only with published validation from someone other than Circular, measured against cuff readings across a range of ages and skin tones. Until that exists, use the ring’s well-presented trend for direction and a cuff for any number you need.
