Apple starts preorders for Watch Series 12, Ultra 4 with new Health Sensing System

Apple used its fall event to pitch the Watch Series 12 and Ultra 4 as a hardware step up, not just a yearly refresh. Both watches get a new Health Sensing System plus the S11 chip, and Apple says that combo delivers the “most accurate heart rate sensing in a wearable.” That’s a strong claim, and the company backed it with changes under the hood.

The new sensing system is built around redesigned photodiodes arranged in a ring, which Apple says capture light more efficiently. It also adds a larger electrode surface area for better skin contact. On top of that, the green LEDs in each watch’s optical heart sensor are said to be bigger and more power-efficient.

Apple says the watches can measure heart rate every five seconds, which is a lot more frequent than the old cadence implied by its pitch. The new system also supports higher-frequency heart rate variability readings than previous Apple Watches. That should make the watches feel less like fitness accessories and more like persistent health trackers.

Users will also get a real-time heart rate view through a new watch face feature — Apple calls it a complication. It’s a small software touch, but it makes the new hardware easier to see in action. Apple clearly wants the health story to do the heavy lifting here, and it’s leaning hard on sensor design rather than flashy redesigns.