Apple Watch Series 12 debuts with updated health sensors and internal design changes

The Apple Watch Series 12 has officially reached retail availability, bringing a suite of internal hardware updates centered on a new Health Sensing System. While the device maintains a familiar aesthetic, Apple has integrated a faster S11 chip and a redesigned rear sensor array that now captures heart rate data every five seconds, even during periods of inactivity. This increased sampling rate is designed to provide more granular insights into how daily activities, such as exercise or stress, influence cardiovascular metrics.

Independent testing of the new sensor array has yielded positive results. In a comparative analysis against a Polar H10 ECG chest strap, the Series 12 demonstrated high accuracy across various activities. The device showed near-identical readings during indoor cycling and maintained a 0.98 correlation with the chest strap during running. While weightlifting proved more challenging, the watch still achieved a 0.97 correlation, placing it among the top-performing wrist-based sensors for that specific activity.

Despite the focus on internal health upgrades, users have noted subtle external modifications. Reports indicate that the Series 12 features slightly larger bezels compared to the Series 11, a change attributed to the increased surface area required for the new sensor stack. Additionally, some users have observed that the Digital Crown appears to protrude slightly further from the case. The aluminum models are now constructed with Ceramic Shield 2, which Apple claims is 60 percent tougher than the previous Ion-X glass.

The Series 12 introduces a new readiness score feature, which synthesizes data from recent activity, sleep, and vitals to help users manage their training intensity. This metric requires approximately one week of data collection to calibrate. While the watch supports faster charging—capable of reaching 12 hours of usage from a 15-minute charge—this functionality is restricted to the specific charger included in the box. The device is available in 42mm and 46mm sizes, with pricing starting at $399.