Apple Watch Series 12 and Ultra 4: AI-Powered Health Features and S11 Chip

Performance Upgrades and the S11 Processor

The primary technical upgrade across both models is the introduction of the S11 processor, which replaces an architecture that had remained largely unchanged since the S9 chip launched in 2023. This new silicon delivers a significant boost in power and reactivity, providing the computational capacity required to run watchOS 27 and handle exclusive functions. This hardware shift allows Apple to process complex sensor data, improving responsiveness for demanding applications and background health tracking.

On-Device Audio Intelligence and Siri Features

Apple Intelligence integration brings several new processing capabilities to the wrist, including Audio Intelligence features that recognize environmental sounds such as doorbells or sirens and alert the user. The watch includes a Live Rewind function that can record up to 15 seconds of spoken audio, letting users read a text transcription of a recent conversation directly on the screen if they miss information. Additionally, a Siri summary tool compiles audio inputs gathered throughout the day. This feature operates with end-to-end encryption and does not store actual voice recordings, with activation controlled manually through the control center or set to run continuously. A dedicated Siri watch face also debuts on the new devices to provide immediate access to AI tools.

Redesigned Health Sensors and Recovery Metrics

Health tracking receives a major overhaul through a redesigned sensor array located on the back of the watch case. Updated electrodes improve the accuracy of continuous electrocardiograms (ECGs), while wider green LEDs measure heart rate every 5 seconds—60 times more frequently than previously. Heart rate variability (HRV) measurements now occur every 5 minutes, representing a 24-fold increase in sampling frequency. Complementing these hardware changes, the Health application introduces a new “Preparation” metric that calculates a recovery score to assess bodily fatigue throughout the day. The interface features a redesigned layout, personalized recommendations driven by Apple Intelligence, and comprehensive health summaries. Users can also view their biological age within a longevity tab to compare physical status against chronological age. Furthermore, a VO2 max test utilizes the front-facing camera of an iPhone to measure respiratory capacity during guided running sessions.

Design Variations and Battery Endurance for Series 12 and Ultra 4

The Apple Watch Ultra 4 extends battery endurance, delivering more than two days of battery life exceeding 48 hours, and up to 18 hours during active exercise tracking, surpassing the 42 hours of the Apple Watch Ultra 3. The Ultra 4 will be available in natural gray and black finishes alongside a new watch band. Meanwhile, the Apple Watch Series 12 maintains 42 mm and 46 mm sizing options while introducing Ceramic Shield protection on the base aluminum model, which includes a new bronze color option. The ceramic case also returns in a pearl white finish alongside a new blue option.