The Apple Watch Series 12 and Ultra 4 keep the familiar look of their predecessors, but their main changes are inside: a redesigned health-sensing system, more frequent heart-rate and HRV readings, updated Vitals, and Apple’s new S11 chip. The Series 12 offers more case materials and finishes; the Ultra 4 is built around longer battery life. Whether either is a worthwhile upgrade depends most on your current watch and how much you value those health features.
What changed in Series 12 and Ultra 4?
In a hands-on review published September 17, 2026, Chance Miller describes both watches as visually similar to their predecessors, with the key changes underneath. Both use Apple’s S11 chip, which Apple calls its most powerful wearable chip. Miller noticed faster app launches and interactions in a brief comparison with Ultra 3; that is an early reviewer observation, not a benchmark. Apple also says S11 supports health sensing, Audio Intelligence, and a redesigned pedometer model. Read the review.
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How do the designs, sizes, and materials differ?
Series 12: more material and finish choices
The review describes Series 12 in aluminum, titanium, and ceramic configurations. Its listed aluminum finishes are Dark Bronze, Light Gold, Black, and Space Gray; titanium comes in Radiant Gold and Natural; ceramic comes in Night Blue and Pearl White. The review reports that the display area is about 2% smaller than Series 10 and Series 11 while retaining the overall pixel count, and that the case is about 1 mm wider. Miller did not notice those differences in ordinary use. These details are the reviewer’s account and should not be treated as a complete current specification list.
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The review lists Ultra 4 in Natural and Black titanium. It also describes a redesigned translucent silicone Ocean Band in translucent gray, translucent kelp, and translucent black, which Miller found lighter-feeling. Band fit depends on the watch case and connector, so check compatibility for the specific watch and band before buying.
#1 Best Overall
![Apple Watch Series 11 [GPS 46mm] Smartwatch with Jet Black Aluminum Case with Black Sport Band - M/L. Sleep Score, Fitness Tracker, Health Monitoring, Always-On Display, Water Resistant](https://m.media-amazon.com/images/I/416RQ0rtsUL._SL160_.jpg)
- A FULL-FEATURED HEALTH TRACKER—Apple Watch Series 11 gives you invaluable insights about your body, right from your wrist. Take an ECG anytime* and get alerts for a high and low heart rate or an irregular rhythm*—so you can stay closer to your heart. You can also view your overnight health tracking metrics with the Vitals app* and be notified of possible sleep apnea.*
- KNOW YOUR SLEEP SCORE—With advanced sleep tracking, Series 11 gives you a daily sleep score. It’s an easy way to help measure and understand the quality of your sleep, so you can make it more restorative.
- GET HYPERTENSION NOTIFICATIONS—Did you know that Series 11 can spot signs of chronic high blood pressure? By analyzing how your blood vessels respond to beats of the heart, it can notify you of possible hypertension.*
- SAFETY FEATURES—A smartwatch that puts your safety first. Series 11 can detect a hard fall or severe car crash, automatically help connect you with emergency services, and notify your emergency contacts.* Check In can automatically notify a loved one when you’ve arrived at your destination.
- A POWERFUL FITNESS TRACKER—With advanced metrics and motivating features like Pacer, Heart Rate Zones, training load, and Workout Buddy powered by Apple Intelligence from your nearby iPhone*—Series 11 is made to help everyone stay active, from runners and hikers to strength-training enthusiasts.
What is new in health sensing?
The review attributes three sensor-design changes to Apple: greater ECG electrode contact area, photodiodes arranged in a ring, and larger green LEDs. It reports heart-rate readings every five seconds whether the wearer is moving or still, compared with an earlier approach that attempted a reading every five minutes while mostly stationary.
Apple says the system achieved statistically better overall accuracy than competing wearables in a study of more than 1,000 participants, and calls it “the most accurate heart rate sensing in a wearable.” Those are Apple claims as reported by Miller. The review does not provide the underlying study, its methods, or its results, so readers cannot independently assess that comparison from this source.
Miller found the denser readings useful for observing everyday activity. He also reports that the Heart Rate app shows a graph of the last two minutes and offers two heart-rate complications. In his short testing period, he did not see a clear change in personal calorie estimates or an improvement in automatic workout detection. Those individual impressions do not establish how the watches will perform for other users.
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Rank #2
![Apple Watch Series 11 [GPS 42mm] Smartwatch with Rose Gold Aluminum Case with Light Blush Sport Band - S/M. Sleep Score, Fitness Tracker, Health Monitoring, Always-On Display, Water Resistant](https://m.media-amazon.com/images/I/31caPPnRysL._SL160_.jpg)
- A FULL-FEATURED HEALTH TRACKER—Apple Watch Series 11 gives you invaluable insights about your body, right from your wrist. Take an ECG anytime* and get alerts for a high and low heart rate or an irregular rhythm*—so you can stay closer to your heart. You can also view your overnight health tracking metrics with the Vitals app* and be notified of possible sleep apnea.*
- KNOW YOUR SLEEP SCORE—With advanced sleep tracking, Series 11 gives you a daily sleep score. It’s an easy way to help measure and understand the quality of your sleep, so you can make it more restorative.
- GET HYPERTENSION NOTIFICATIONS—Did you know that Series 11 can spot signs of chronic high blood pressure? By analyzing how your blood vessels respond to beats of the heart, it can notify you of possible hypertension.*
- SAFETY FEATURES—A smartwatch that puts your safety first. Series 11 can detect a hard fall or severe car crash, automatically help connect you with emergency services, and notify your emergency contacts.* Check In can automatically notify a loved one when you’ve arrived at your destination.
- A POWERFUL FITNESS TRACKER—With advanced metrics and motivating features like Pacer, Heart Rate Zones, training load, and Workout Buddy powered by Apple Intelligence from your nearby iPhone*—Series 11 is made to help everyone stay active, from runners and hikers to strength-training enthusiasts.
How Readiness and Vitals work
Readiness combines several signals
As described in the review, Readiness draws on recent activity, training load, vitals, and sleep score. It can update during the day in response to naps, activity, and daytime heart rate, but it needs a week of sleep data before it can produce a score. The review describes Apple’s scale as:
- 0–1: Recover
- 2–4: Pace Yourself
- 5–7: Ready
- 8–10: Go For It
Miller had only one score after a week of use, so he could not judge its longer-term usefulness. Treat Readiness as an additional prompt to consider alongside how you feel and your training plan, rather than as a proven standalone measure of recovery.
More HRV readings and a daytime Vitals view
The review says HRV sampling may happen as often as every five minutes at rest, compared with once every two hours previously, and notes a new recovery HRV measurement. It also describes a daytime Vitals view with four categories—“notably off,” “slightly off,” “typical,” and “favorable”—rather than a two-category approach.
Rank #3
![Apple Watch Series 11 [GPS 42mm] Smartwatch with Jet Black Aluminum Case with Black Sport Band - S/M. Sleep Score, Fitness Tracker, Health Monitoring, Always-On Display, Water Resistant](https://m.media-amazon.com/images/I/41s72HIk5TL._SL160_.jpg)
- A FULL-FEATURED HEALTH TRACKER—Apple Watch Series 11 gives you invaluable insights about your body, right from your wrist. Take an ECG anytime* and get alerts for a high and low heart rate or an irregular rhythm*—so you can stay closer to your heart. You can also view your overnight health tracking metrics with the Vitals app* and be notified of possible sleep apnea.*
- KNOW YOUR SLEEP SCORE—With advanced sleep tracking, Series 11 gives you a daily sleep score. It’s an easy way to help measure and understand the quality of your sleep, so you can make it more restorative.
- GET HYPERTENSION NOTIFICATIONS—Did you know that Series 11 can spot signs of chronic high blood pressure? By analyzing how your blood vessels respond to beats of the heart, it can notify you of possible hypertension.*
- SAFETY FEATURES—A smartwatch that puts your safety first. Series 11 can detect a hard fall or severe car crash, automatically help connect you with emergency services, and notify your emergency contacts.* Check In can automatically notify a loved one when you’ve arrived at your destination.
- A POWERFUL FITNESS TRACKER—With advanced metrics and motivating features like Pacer, Heart Rate Zones, training load, and Workout Buddy powered by Apple Intelligence from your nearby iPhone*—Series 11 is made to help everyone stay active, from runners and hikers to strength-training enthusiasts.
Which one better fits your battery needs?
The following figures are manufacturer estimates reported in the review, not independent battery-test results. Workout figures are also Apple-reported values as relayed by Miller.
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| Use case | Series 12 | Ultra 4 |
|---|---|---|
| Normal use | 24 hours | 50 hours |
| Low Power Mode | 38 hours | 84 hours |
| Outdoor or workout tracking | 10 hours outdoors | 18 hours standard workouts; 25 hours Extended; 45 hours Max Extended |
The review says Series 12’s normal-use and Low Power Mode estimates match Series 11’s claims. It compares Ultra 4’s figures with Ultra 3’s reported 42 hours of normal use and 72 hours in Low Power Mode.
Miller reports charging his Ultra 4 around 8 p.m. Sunday and again around 8 p.m. Tuesday—about 48 hours later. During that period he tracked 90 minutes of workouts, spent three hours away from his iPhone, and tracked sleep for two nights. This is one person’s use period, not a controlled battery test or a guarantee of typical runtime.
Rank #4
![Apple Watch Ultra 3 [GPS + Cellular 49mm] Running & Multisport Smartwatch w/Rugged Titanium Case w/Blue/Bright Blue Trail Loop - M/L. Satellite Communications, Advanced Health & Fitness Tracking](https://m.media-amazon.com/images/I/51SKumOyv8L._SL160_.jpg)
- RUGGED AND READY TO GO—The ultimate sports and adventure smartwatch is built to last with an extremely tough titanium case and a strong sapphire crystal display. Water resistant up to 100m—it’s great for swimmers, divers, and fans of high-speed water sports.*
- A FULL-FEATURED HEALTH TRACKER—Ultra 3 can take an ECG* and check your heart rhythm for signs of AFib—right from your wrist. The smartwatch sends alerts for possible hypertension,* an irregular heart rhythm,* or an unusually high or low heart rate. You can view your overnight health tracking metrics with the Vitals app,* track your sleep score, and take readings of your blood oxygen.*
- ULTIMATE RUNNING AND WORKOUT COMPANION—A superior fitness tracker for marathoners, triathletes, mountain bikers, backcountry hikers, and mountain climbers, Ultra 3 provides precision dual-frequency GPS, Pacer, Heart Rate Zones, Custom Workouts, running power, Workout Buddy powered by Apple Intelligence from your nearby iPhone,* training load, and more.
- KEEP HELP CLOSE AT HAND—Ultra 3 is a smartwatch that can detect a hard fall or severe car crash* and automatically help connect you to emergency services and notify your emergency contacts. Check In can automatically notify a loved one when you’ve arrived at your destination.
- MULTIDAY BATTERY LIFE—Ultra 3 is a smartwatch that’s engineered to give you even longer battery life. It’s perfect for trail runners—with up to 42 hours of normal use and up to 72 hours in Low Power Mode.* Track a workout with full GPS and heart rate monitoring for up to 20 hours in Low Power Mode.*
Should you upgrade from your current Apple Watch?
Consider it if you have Series 9 or Ultra 2
Miller specifically identifies Series 9 and Ultra 2 owners as people with more reason to consider upgrading. The case is strongest if you want the redesigned sensing system, more frequent heart-rate and HRV readings, Readiness, or the updated Vitals presentation. The cited review does not establish a current price or local availability, so compare the actual cost of changing watches where you live before deciding.
Think carefully if you have a newer model
For owners of newer watches, the reviewer’s advice is to weigh interest in the health changes against the familiarity of the hardware design. If those new measurements and summaries do not matter to your routine, the review gives no independent value analysis showing that a newer watch is a necessary upgrade.
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- Choose Series 12 if you want the Series line and its wider range of case materials and finishes, and its reported battery estimates suit your charging routine.
- Choose Ultra 4 if longer manufacturer-rated runtime and extended workout tracking better match your outdoor or multi-day use, and you prefer its titanium construction.
Which software features were still pending in the review?
The September 17, 2026 review described a redesigned Health app, including a Longevity tab and Health Age, as part of a later software update and available in beta at that time. It also described Live Rewind and Siri Recap as expected later in the year, with beta timing. Those statements record the software status reported on that date; check Apple’s current release information before relying on any of these features as available.
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