Apple Watch Series 12 delivers the most accurate heart rate sensing in a wearable, with higher-frequency heart rate and heart rate variability (HRV) measurements enabled by the new Health Sensing System and the S11 chip. These measurements power a readiness score that analyzes recent activity, training load, vitals, and sleep to give a 0-10 rating with actionable advice such as Recover, Pace Yourself, Ready, or Go For It.
The article explains that the new Health Sensing System and S11 chip enable higher‑frequency heart rate and heart rate variability readings, which power the readiness score ranging from 0 to 10 with actionable advice.
The Health app on iPhone has been redesigned to include a Longevity tab that shows Health Age--how a user's metrics track relative to their actual age--and an Insights tab that surfaces timely health information across heart, sleep, readiness, fitness, vitals, and cycle tracking data, updated throughout the day.
As described in the article, the redesigned Health app includes a Longevity tab that shows Health Age—how a user's metrics track relative to their actual age—and an Insights tab for timely health information.
Battery life has been extended for workouts: Apple Watch Series 12 offers up to 10 hours of battery life during an outdoor workout, which is 25 percent more than the previous model. Charging is also faster, with 15 minutes providing up to 12 hours of additional battery life, a 50 percent improvement over the prior generation.
Step tracking has been improved through a completely redesigned pedometer model and new machine-learning algorithms, giving Apple Watch Series 12 the most accurate step tracking of any smartwatch. The S11 chip enables a real-time Steps complication on the watch face.
Audio Intelligence features introduced with watchOS 27 include Sound Recognition, which alerts users to important sounds like sirens or doorbells; Music Recognition with Shazam, which identifies background songs and displays them in the Smart Stack; Live Rewind, which shows a text snippet of the last 15 seconds of speech when the Digital Crown is double-pressed; and Siri Recap, which creates high-level summaries of conversations to jog memory. All Audio Intelligence processing occurs in the S11 chip's Secure Enclave, and no audio is recorded or stored, with end-to-end encryption for saved summaries via iCloud.
The article notes that watchOS 27 introduces Audio Intelligence features such as Live Rewind, which provides a text snippet of recent speech without recording or storing audio, processed securely in the S11 chip’s Secure Enclave.