Apple Unveils Watch Series 12 and Ultra 4, Details 2nm-Derived S11 Chip

Apple has further disclosed technical details of the new S11 system-in-package (SiP) chip that powers its next-generation smartwatches, following the official launch of the Apple Watch Series 12 and Apple Watch Ultra 4. The S11 is derived from the 2-nanometer A20 Pro chip architecture used in the iPhone 18 Pro and the foldable iPhone Duo. It integrates two high-efficiency CPU cores optimized on that architecture, a single-core graphics processing unit (GPU) and a four-core neural processing engine (AI accelerator). By scaling the core design of the A20 Pro down to a wearable platform, the S11 improves routine system interaction, complex watch-face rendering and standalone app launch speeds, while delivering local hardware-level machine learning within the power and thermal budget of a wrist-worn device.

The Apple Watch Series 12 and Ultra 4 carry a new health-sensing hardware system. Leveraging the real-time data throughput and low-power background processing of the S11, continuous all-day heart-rate sampling runs once every five seconds, a data sampling density 60 times that of the previous generation. Heart rate variability (HRV) monitoring granularity has been shortened from once every two hours to once every five minutes.

The four-core AI compute unit of the S11 supports a system-level feature called Audio Intelligence. Combining the watch's multi-array microphones with a local neural network, the feature identifies critical environmental danger sounds such as doorbells and fire alarms, providing haptic alerts for the hearing-impaired. It supports rapid transcription of the last 15 seconds of a conversation entirely offline, and generates local condensed summaries of meetings and everyday conversations. Audio capture and text analysis run independently within the secure enclave of the S11's on-device chip, with no raw audio uploaded to the cloud.