Apple's New Watch Looks the Same but Measures More
Apple's Watch Series 12 looks the same as before. The buttons, sizes and sensor types are unchanged. The changes are inside, in the chip and the health sensors. That is the finding after a week of testing described in a review published September 17. The Verge
The outside is the same. The inside is new. Series 12 and Ultra 4 use a new S11 chip. It is faster at general tasks, graphics and AI work, and it has a secure exclave, a separate locked-off part of the chip that handles microphone sound.
The health sensors are also redesigned. The contacts that read the heart's electrical signal are larger. The light sensors and lights that track blood flow are rearranged and larger, and the lights use less power.
That hardware allows three changes. First, heart rate is checked much more often. Apple states that Series 12 with the Health Sensing System and S11 delivers higher-frequency heart rate and heart rate variability measurements. Apple In practice, Series 12 measures heart rate every five seconds at rest and during activity. Older Apple Watches measured once every five minutes when not in a workout. It is like checking the weather every few minutes instead of a few times a day.
Second is a new readiness score. Apple describes the readiness experience on Series 12 and Ultra 4 as "giving users insight into the body's capacity to take on the day." Apple
Third is Audio Intelligence, listening features that use Apple Intelligence. One part is Siri Recap, which makes notes from conversations. The exclave matters here. Because microphone sound stays in its own separate hardware path, questions about privacy, delay and battery use are addressed directly.
Apple also makes a claim about accuracy. Apple states that the Health Sensing System enables "the most accurate heart rate sensing in a wearable." To support that, Apple published a paper comparing Series 12 to the Polar H10 chest strap, Pixel Watch 4, Galaxy Watch 8, Oura Ring 5 and Whoop. Independent testing so far is limited but consistent. In the review testing, Series 12 stayed within five beats per minute of the Polar H10 chest strap during two runs, a walk and at rest. The Verge
Several health and AI features were not ready at launch and were not covered in the review. They are planned for later in the year. What is on sale now runs watchOS 27 and costs $399, with availability starting September 18. The Verge Series 12 also comes in ceramic, the first ceramic Apple Watch option since the Series 5 in 2019. The Verge
The broader context here is where smartwatch progress now comes from. For several years, gains came from bigger screens, thinner cases or new wireless parts. This time the change is how often the watch measures and how much it can process on the watch itself. More frequent checks change what apps can learn from heart patterns. Better contacts and lights improve the signal at the source. A faster AI processor means less need to send data to a phone.
In my view, that mix matters more for coaches, developers and researchers than the readiness score alone. Steady heart data that closely matches a chest strap could be useful for fitness coaching, managing tiredness and long-term health studies, if testing beyond Apple's paper and a few runs confirms it. The listening features point the same way. If conversation notes can work reliably while staying private and power-efficient, the watch records daily life as well as health. Both ideas will depend on the software that was not ready to test at launch. The hardware sets the upper limit. The delayed software will set the lower limit.
