Apple's new Health Sensing System for Apple Watch Ultra 4 means more accurate and more frequent health metric tracking. It feels like the peak offering of a device before a necessary complete redesign.
Nearly every improvement made to Apple Watch Ultra 4 relates to health, fitness, and the ability to track those metrics. Even the longer battery life was pitched as a way to track metrics over a longer period of time.
Tim Cook may have stepped down as CEO before Apple Watch Ultra 4 was revealed, but it and the Apple Watch Series 12 are clear realizations of his vision. Apple Watch is a health-focused wearable that aims to improve the wearer's life, and perhaps even save them in emergency situations.
Out of all of Apple's products, the Apple Watch is perhaps the most mature with very little wiggle room, even when compared to the Apple TV — there just isn't enough space. That is clear given that even the Apple Watch Ultra 4 gained a gram in weight thanks to the new sensor system.
The Apple Watch Ultra line appears to be in an even more awkward position compared to the standard "Series" line. It has consistently received all of the updates brought to models like Apple Watch Series 12 (on sale now), but nothing "Ultra" has been added or upgraded since the original model's launch.
As I pointed out in my Apple Watch Ultra 3 review, it's still the larger, high-end watch with the most sensors and ruggedness. However, Apple seems stumped on how to iterate on the premium Apple Watch beyond keeping it in lock step with the rest of the lineup.
That said, the 2026 model at least is a significant step forward. Here's what Apple Watch Ultra 4 offers.
When you're looking at Apple Watch Ultra 4 on someone's wrist, you'll never guess which generation it is from design alone. Apple has stuck with the same design since the original launched, though the black option did arrive as a change in gen 2.
Apple Watch Ultra 4 review: Same design, color, and orange Action button
Flip it on its back and you'll see a significant difference thanks to the new Health Sensing System. Apple has replaced the sensor stack with updated components for more frequent and more accurate readings.
The electrodes are larger, which surround the photo diodes where green LEDs are shown through to collect data. This all fits in the Apple Watch, though there has been a weight increase of about 1.4 grams.
It's such a small change that I haven't noticed a difference.
The display is identical across generations, you're getting the same 100m dive spec, and it is still a titanium case with orange accents. I do think Apple could have made a statement with a new case color or design tweak, but that wasn't for this year.
Much of what was introduced in Apple Watch Ultra 4 and Apple Watch Series 12 is tied to the updated Health app coming in iOS 27.2. I've tested the Watch with and without this update, but I won't spend too much time on the app itself here.
Apple Watch Ultra 4 review: Every upgrade can be tied to S11 and new sensors
All of the metrics that matter most on Apple Watch saw a boost with the new system. These upgrades come at no loss of battery life, and even then, Apple says the battery life has increased in the latest generation.
Here is every new feature for Apple Watch Ultra 4:
There's also the new Readiness app, but I've not had enough nights of data collection for it to show anything just yet. It gathers data over a week, and as this is published, it has been a week since getting the device. I'll discuss Readiness when I write more about the new Health app, which deserves its own full breakdown.
All of these new sensors add up to a new health-forward platform that should excite anyone that likes putting data in databases. Your heart rate is read every five seconds and HRV data is collected every five minutes.
Heart Rate Variability has become a popular way to measure a person's overall health, mostly due to products like the Whoop health band. Apple already collected this data, but it is putting it front and center with the Apple Watch Ultra 4.
Apple Watch Ultra 4 review: Feeding more data into Apple Health
I personally don't care about any individual health metric, but the idea of getting more data that's more accurate is appealing to me. I want my new Apple Health app with Apple Intelligence to have every bit it can to help with my health journey.
I don't feel the need to detail every Apple Watch Ultra feature, as they should be fairly well-known by now. It's a rugged smartwatch that can withstand extreme conditions, has a siren for emergencies, can make emergency calls via satellite, and has a much longer battery life than standard Apple Watches.
Apple Watch Ultra 4 has identical wireless specs with Wi-Fi 4, Bluetooth 5.3, and 5G.
The Apple Watch Ultra 3 was my first Apple Watch Ultra, so I broke down the smaller details in that review. That's the thing — Apple's Ultra updates lack new "Ultra" features, so rehashing identical feature lists seems redundant.
Apple Watch Ultra 4 review: This is an Apple Watch Ultra 3, but you wouldn't have known that without being told
The base feature set exclusive to Apple Watch Ultra hasn't changed since the original model beyond satellite connectivity. I'm glad Apple has added the S11 and the benefits provided by that chipset, but we're not seeing anything else.
That chipset is what enables many of the upgrades without sacrificing battery life. The S11 has a neural engine derived from the A20 Pro used in iPhone 18 Pro (check deals), which enables new AI features.
