I’ve worn the Apple Watch Series 12 for a week — the biggest changes are underneath

Now, I typically wear an Apple Watch daily, and have since the wearable launched in spring 2015, but for the past week, I’ve swapped my Ultra 3 or Series 11 for the Apple Watch Series 12.

Unveiled at Apple’s September 9, 2026, ‘Surprise and shine’ event , the next-generation mid-range Apple Watch — err, flagship for everyone in between the SE third-gen and Ultra 4 — doesn’t change much in terms of looks over the Series 11, but does usher in a redesigned rear as part of a new health-sensing system, a new SoC under the hood to power some new features, and a good bit of AI on top of what we knew was coming with watchOS 27 .

And while I do have a full review coming, I’m waiting to gather more data and get my first taste of a Readiness Score — Apple’s fresh take on contextualizing all your data in an upgraded Vitals experience that I’m pretty stoked to try.

In most cases, it will take just seven nights of wear to calculate.

While there are new case types — Ceramic arrives alongside Titanium and Aluminum — the Series 12 design is very similar to the Series 11.

You can pick between a 44mm or a 46mm display, and it’s still an Always-On OLED that goes pretty close to the edges and even curves down a bit.

I’ve specifically been testing the black aluminum, which looks fine and a bit plain — more importantly, it retains the slim profile. (Image credit: Future/Jacob Krol) Thankfully, all your previous bands will still work, but on the back you’ll see the new health-sensing system.

The layout is different; it looks almost like a sundial with new placements for electrodes and diodes.

Apple also swapped in a green LED, which is more efficient at getting readings.

Despite the changes, the watch still sits on the wrist just as well.

Of course, it still protrudes a bit from the back; see the photo below.

This, in conjunction with the new S11 chip, which is actually a derivative of the A20 Pro in terms of design and components, makes use of a Secure Enclave and an always-on processor section to improve sampling rates.

This is the big ‘aha’ achievement, as it lets the Apple Watch track HRV and real-time heart rate whether you open the app or use the complication, and it also speeds up pedometer performance for faster step tracking. @techradar ♬ original sound - TechRadar Heart rate variability is a really sweet metric to have, and its arrival on the Apple Watch brings it closer to some competitors.

This will also inform the Readiness Score.