Apple Watch Series 12 and Ultra 4 launch with advanced health sensors

Apple has released the Apple Watch Series 12 and Ultra 4, featuring the new S11 chip and a redesigned Health Sensing System. This new system enables high-frequency heart rate monitoring every five seconds and improved heart rate variability (HRV) tracking, which powers a new Readiness score.

However, the increased sensor frequency causes the green LED to flash more often, prompting the introduction of a Theater Mode to reduce light visibility and save battery. Users can manually adjust settings to maintain continuous measurements even in Theater Mode. Additionally, the new models include a native step count complication on the watch face, though this feature is exclusive to the latest generation.

New audio intelligence features, such as Siri Recap and Live Rewind, allow the devices to transcribe and summarize ambient conversations. While Apple states that audio is encrypted and not stored as traditional recordings, the feature has raised privacy and social context concerns regarding ambient surveillance.

Early adopters have reported technical issues, specifically sudden device reboots. Diagnostic logs suggest these crashes are linked to the Apple Neural Engine timing out, triggering a kernel panic and subsequent restart. Apple is also working on watchOS 27.2 beta to restore the App Switcher via a new gesture.