The Apple Watch Series 12 looks nearly identical to the Series 11, but Apple has reintroduced a Ceramic case option in white or blue, alongside a new "dark bronze" aluminum finish and "radiant gold" titanium. Aluminum models now feature Ceramic Shield 2, matching the iPhone 18 Pro, while Titanium and Ceramic retain sapphire-crystal displays. The most significant upgrade is the new health sensing system, which increases skin-contact surface area and packs diodes, electrodes, and LEDs more densely.

This enables background heart rate measurements every five seconds instead of every five minutes, and HRV readings as often as every five minutes. The system also adds RMSSD calculations for better workout insights, feeding into the updated Vitals app and a new Readiness score. Apple follows competitors like Garmin, Fitbit, Samsung, Google, and Oura Ring in offering readiness metrics, though the reviewer finds limited personal utility.

The controversial audio features mentioned in marketing remain unavailable at launch.