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Apple Watch Series 12 vs Circular Ring 2: Full Comparison
I wore both the Circular Ring 2 and the Apple Watch Series 12 for 14 days. Ring on the left index, watch on the left wrist, and a Polar H10 on for every workout to keep them honest. Fourteen days is enough to find what spec sheets hide. Disclosure: I work at Circular. I’ve tried to make this useful anyway, which mostly means telling you the three things about our own ring that annoyed me. Here’s what I discovered, along with the areas where each product actually falters.
Specs Comparison
FeatureApple Watch Series 12Circular Ring 2Price$399 (42 mm GPS)$349Weight31.5-44.9 g2-3 gThickness9.7 mm2.8 mmBatteryUp to 24h (38h Low Power)Up to 8 days (Eco)Charging80% in ~30 min30 min (case charger)ECGSingle-lead, 30sSingle-lead, 40sBlood PressureHypertension notifications (no mmHg)Cuffless BP estimate (mmHg, calibration)Sleep trackingNative app + stages + scoreFull stages + HRV + SpO2 + temperatureHeart rateContinuousEvery 2 minSpO2 (blood oxygen)On-demand spot checkContinuous overnightAI coachingSiri + Vitals appKira AI (built-in coach)Best forWorkouts, notifications, apps24/7 health, sleep, recoveryNumber of Core FeaturesApp ecosystem14+ core featuresECG Sensor & AFib DetectionYes (single-lead ECG)Yes (single-lead ECG, FDA-cleared algorithm)MaterialsAluminum, titanium, ceramicTitanium + metallic coating on the outside & hypoallergenic epoxy resin on the insideSubscriptionNo subscription (iPhone required)No subscription on 14 core features (premium freemium)Energy & Chronotype AnalysisReadiness score (0-10)Energy score (0-100). Kira analyzes chronotype to tell coffee, work, activity, sleep, wind down windowsFall DetectionYesNoCrash DetectionYesNoEmergency SOSYesNoSleep Apnea NotificationsYesNo (continuous SpO2 + sleep stages)Women's Health ToolsYes (Cycle Tracking, ovulation)Yes (Cycle Tracking, ovulation)
Quick Take: Which one should you buy?
For most people, I’d go with the Circular Ring 2. It’s a ring, so it’s tiny and comfortable to sleep with every night, and you barely notice it’s there. The Apple Watch makes sense mainly if you want live workout metrics, notifications, and apps on your wrist.
Choose the Apple Watch 12 if:
- You want a second screen for your iPhone, with live heart rate and pace during a run.
- You want built-in GPS and notifications on your wrist.
- You want a broad ecosystem of apps and third-party health integrations.
Choose the Circular Ring 2 if:
- You want something so small you forget you’re wearing it, even in bed.
- You want to track long-term trends, sleep, recovery, and temperature tracking all night, every night.
- You don’t want to charge a device every single day.
Apple Watch 12 vs Circular Ring 2: Design and Comfort
Winner: Circular Ring 2
The Apple Watch Series 12 is 9.7 mm thick and weighs between 31.5 and 44.9 grams depending on case size and material. You feel it when you type, when you sleep on your side, when you slide a jacket over it.
The Circular Ring 2 weighs 2 to 3 grams and is 2.8 mm thin. By day three I stopped noticing it. It disappears the way a plain ring disappears.
The Apple Watch looks like a smart device, even though wearing one is hyped right now. The ring feels like natural jewelry: titanium with a metallic coating on the outside so most people won’t notice it’s a smart device until you tell them.
At night the gap widens. I found the Apple Watch uncomfortable to sleep in. The ring, I didn’t notice at all.
One real downside of the ring: the size is fixed, and fingers swell. In summer heat, or after a salty meal, a ring that fits at 2pm can be tight at 9pm. There is no buckle, no strap, no half-size to slide to. If your finger changes size, you change where you wear your ring or buy a new ring, not a new notch.
On sizing: Circular ships a sizing kit so you confirm your exact size before the ring arrives, and there’s also a digital sizing tool that guesses your size from a photo of your hand on your phone.
Apple Watch 12 vs Circular Ring 2: Sleep Tracking
Winner: Circular Ring 2
Ring reviews love to say the Apple Watch can’t track sleep. It can. Sleep app in watchOS 7, sleep stages in watchOS 9, a sleep score on recent models. No third-party app needed.
The software isn’t the problem. The problem is that the watch has to be somewhere at 11pm, and for most people that somewhere is a charging puck.
I charged the watch at night for the first week, like a normal person. Seven nights, zero sleep data. Then I moved the charge to my morning shower, which worked, and which meant remembering a small chore every day for a month. I forgot twice. The Circular Ring 2 has no screen and no GPS, so it produces no light at night and never disturbs you or the person next to you.
My sleep score climbed over the 14 nights, from 77 to 92 for Circular and from 68 to 96 for the apple watch. Both apps show the same trend, a single 0-100 number, but they build it differently. Apple’s sleep score weighs time asleep and time in each sleep stage. Circular’s sleep score is more complete as it also folds in HRV, blood oxygen saturation, body temperature, and how consistent your sleep has been across the week.
One thing about the finger: it sits closer to core blood flow than the wrist, so finger temperature tracks your internal temperature more faithfully and is less thrown off by ambient air. That is the mechanism behind the ring’s edge on overnight temperature and cycle tracking.
The ring also has a Smart Alarm: you set a wake window, and it triggers your phone’s alarm during your lightest sleep phase, so you wake less groggy. The ring itself does not vibrate; the alarm plays from your phone. The Apple Watch has a standard alarm that buzzes at the exact time you set.
Apple Watch 12 vs Circular Ring 2: ECG & Heart Health
Winner: Apple Watch
Both devices run a single-lead ECG for atrial fibrillation (AFib) screening. The Apple Watch asks you to hold the digital crown for 30 seconds. The Circular Ring 2 asks you to rest a finger from your opposite hand on the ring for 40 seconds.
On the ECG claim, I have to be precise. The Apple Watch’s ECG function has had FDA clearance since 2018 and Circular’s ECG runs on an FDA-cleared algorithm.
In my checks, the Apple Watch ECG reported 59 bpm while the Circular Ring 2 ECG reported 58 bpm. For reference, the Polar reported 57 bpm so I don’t really know which one of them was accurate. Still, I’d give the edge to the watch on heart data. It has years of third-party validation, and a much bigger ecosystem of heart-health studies. For a one-off check or a clinical-grade reading, the watch is the stronger tool.
Apple Watch 12 vs Circular Ring 2: Blood Pressure
Winner: Circular Ring 2
This is a feature the two devices diverge the most on. The Apple Watch Series 12 never gives you a systolic or diastolic number, it offers hypertension notifications, which flag when your readings may be trending high. Apple’s feature reads how your blood vessels respond to each heartbeat, using the optical sensor alone, and runs that analysis passively across 30-day windows.
The Circular Ring 2 gives you a systolic and diastolic estimate.
What each device actually gives you
Apple Watch Series 12Circular Ring 2Gives a systolic/diastolic numberNoYes, as an estimateHow it worksOptical sensor analyses vessel response passivelyECG + PPG measure pulse wave transit timeAnalysis window30 days before it can flag anythingPer measurement, on demandCuff neededApple recommends one after an alertYes, three readings at setup, one every 30 daysWho can use it22+, not if already diagnosed with hypertension, not during pregnancyNo age or diagnosis restriction, it is a wellness featureWhat you do with itTake the alert to a doctorWatch your own trend between doctor visits
The Circular Ring 2 estimates both mercurial numbers. Every heartbeat produces two events the ring can time. An electrical one, the R peak on the ECG. A mechanical one, the pressure wave arriving at your finger, which the PPG sensor sees as a change in light absorption.
It measures pulse wave transit time (PWTT) which is the delay between them, then converts it into pressure using a cuff calibration you do once. Three cuff readings at setup anchor the estimate to your body, and one reading every 30 days keeps it anchored as your arteries drift.
Apple Watch 12 vs Circular Ring 2: Fitness and Workouts
Winner: Apple Watch
The Apple Watch was built for that category and here is why I mean that. The pace, distance, heart rate and calories are shown on a bright OLED display in real time while you run. It has built-in GPS so you can leave your phone at home. It supports dozens of different types of workouts and it automatically recognizes walking, cycling and running.
The Circular Ring 2 has over 50 sport modes and doesn’t have a screen, but it can use your phone’s GPS to log routes, distance and pace. You can also launch a session through the app and leave your phone at home. But you can’t look at your stats in the middle, you do check your stats on your phone during or after the run.
I compared both against a Polar H10 chest strap. At rest and on steady runs, both matched the strap within 5 BPM at rest. Under a barbell, the story changes: the ring’s PPG drops off when you grip hard, because squeezing the bar changes the blood flow under the sensor. I stopped trusting the ring’s heart rate during weightlifting. Because of the wrist position the watch held up better there.
On a run, the watch tracks some metrics that the ring don’t track like split times and estimated VO2 max, all live on your wrist with no phone needed. The ring logs pace, distance, steps, heart rate zones, GPS route, and elevation through your phone’s GPS but you can’t see all of them it until the run is over. The watch is the clear winner for real-time, phone-free training data.
Apple Watch 12 vs Circular Ring 2: Smart Features and Notifications
Winner: Apple Watch
The Apple Watch is a second screen for your iPhone. It mirrors notifications, answers calls, replies to messages, shows your calendar, and controls music.
The Circular Ring 2 doesn’t have a screen and doesn’t vibrate for your notifications. Every number it collects, you read on your phone. Every alarm, your phone rings instead. So for anyone who wants notifications and apps on the wrist, the watch is also the clear winner.
Apple Watch 12 vs Circular Ring 2: Data and App Experience
Winner: Circular Ring 2
Apple Health aggregates steps, heart rate, sleep, cycle tracking, and more. It has grown real intelligence: the Trends feature surfaces long-term changes, and the Vitals app flags overnight metrics that fall outside your normal range. Series 12 even adds hypertension notifications.
Where it falls short is narrative. Apple Health hands you the data and mostly leaves you to interpret it.
The Circular app does the opposite: every morning it produces a single report on sleep, recovery, heart rate, blood oxygen saturation (SpO2), and temperature, then passes the numbers to Kira, Circular’s built-in AI health coach, who turns them into specific recommendations.
In my test, Kira told me to cut caffeine after 4 PM to protect my sleep and suggested winding down earlier. It also mapped my peak energy windows from my chronotype so I could schedule deep work at the right time. Kira reads the numbers so you don’t have to.
One morning, Kira flagged four overnight changes at once: my heart rate variability (HRV) had fallen to 38 ms from a usual range of 52 to 61 ms, my skin temperature ran 0.7°C above baseline all night, my breathing rate climbed to 17.4 breaths per minute from a typical 14.2, and my resting heart rate sat 8 beats per minute above normal. Reading these together, Kira concluded I was under physiological strain and told me what to do: skip intense training, hydrate and go to bed early, get 10 to 15 minutes of morning daylight, and run a five-minute Coherence session in the afternoon.
The Circular Ring 2 is the only smart ring with ECG and more than 13 core health features, with no subscription. Learn more
Apple Watch 12 vs Circular Ring 2: Battery Life
Winner: Circular Ring 2
The Apple Watch lasts up to 24 hours on a charge, or 38 hours in Low Power Mode, and charges to 80% in about 30 minutes. In practice I charged it every day. When you forget to charge it for a single day, you end up not being able to track your sleep.
The Circular Ring 2 lasts up to 8 days in Power mode, and about 6 days in Performance mode in my use with continuous SpO2 and temperature tracking on. When it needs power, you drop it into its case, which has a built-in battery, and it is full in 30 minutes. Over the 14 days I charged the ring twice, and the watch every day.
Apple Watch 12 vs Circular Ring 2: Pricing
Winner: Circular Ring 2
The Apple Watch Series 12:
- Starts at $399 for the 42 mm GPS model.
- Cellular connectivity starts at $499, plus a carrier plan.
- AppleCare+ adds a monthly fee on top.
The Apple Watch requires an iPhone and, for cellular, a subscription plan.
The Circular Ring 2:
- Costs $349, once.
The Circular Ring 2 is for both Android and iOS. Without subscription: the 14+ core features, including ECG, blood pressure, continuous vitals, sleep tracking, and Kira’s daily insights, are free with the ring. A small set of premium features uses a freemium model with a separate fee.
Apple Watch 12 vs Circular Ring 2: Verdict
If I could only keep one, I’d pick the Circular Ring 2. Sleep and recovery matter more to me than a second screen on my wrist, and I’d rather not charge a device every day. But that’s just me, and I’m saying it knowing the ring’s three annoyances: it doesn’t fit if your fingers swell, its heart-rate reading falls apart under a heavy barbell, and it is a paperweight without your phone.
If you’re a runner who wants live pace and GPS on your wrist, someone who wants notifications without reaching for your phone, or a lifter who needs a device and heart rate that survives a heavy grip, buy the Apple Watch.
I found the two devices complementary, not interchangeable, and definitely not integrated. They do not sync with each other. Wearing both worked because they covered different gaps: the watch handled live workout metrics and notifications, the ring handled overnight recovery and long-term trends. The overlapping metrics, heart rate and HRV trends, generally agreed. Whether wearing both is worth roughly $750 total depends on how much you care about health data and especially sleep data.
Ready to experience it yourself?
ECG, sleep tracking, 140+ biomarkers analyzed daily by Kira AI. No subscription on core features.
Take the Quiz: See Where You Stand
Frequently Asked Questions
Q: Can the Circular Ring 2 replace my Apple Watch?
A: For sleep, recovery, and 24/7 health trends, yes, and it does this better because you wear it all night without charging. For live workout data, notifications, and apps, no; the Apple Watch is still the better tool.
Q: Does the Circular Ring 2 work with Apple Health?
A: Yes. Circular syncs heart rate, HRV, SpO2, sleep stages, and respiratory rate to Apple Health, so your data stays in one place.
Q: Is the ECG on the ring as accurate as the Apple Watch?
A: Both are single-lead ECGs. The Apple Watch’s ECG function has had FDA clearance since 2018; Circular’s ECG runs on an FDA-cleared algorithm. In my test both matched a chest strap within 5 BPM at rest.
Q: Which is better for sleep tracking?
A: The Circular Ring 2, but not because the Apple Watch cannot do it. The ring wins on comfort and battery: it’s so small you don’t feel it in bed, and it lasts many days, so it never misses a night.
Q: Do I need a subscription for the Circular Ring 2?
A: The 14+ core features are free with the ring. A small set of premium features uses a freemium model, so those carry a separate fee, but the essentials are included in the purchase price.
References
- Apple Watch Series 12 Technical Specifications, Apple Inc.
- Circular Ring 2 Product Page, Circular.
