Apple Watch Series 12 and Ultra 4 share a new sensing system

The S11 chip supports more frequent heart-rate and variability measurements.

Capvise MediaEvent 9 Sept 2026Published 15 Oct 20261 min read

Photo: Earlier or representative hardware photograph: Apple watch1. The pictured model differs from the product discussed in this report. Credit: Rberchie, “Apple watch1.jpg,” Wikimedia Commons, CC BY-SA 4.0. Adapted by resizing and WebP re-encoding. · CC BY-SA 4.0 · Resized for web delivery

Shared sensors, different endurance

Apple announced Watch Series 12 and Ultra 4 on 9 September, both using the S11 chip and a new Health Sensing System. Apple says more frequent heart-rate and heart-rate-variability readings feed a readiness score. Ultra 4 adds a stated outdoor-workout tracking limit of up to 45 hours.

The announcements also described future software: a redesigned iPhone Health app and Audio Intelligence features were scheduled for later in the year. Those should not be mistaken for capabilities available on announcement day. The two models share a substantial health platform, while Ultra’s endurance and outdoor positioning address a different use case. Apple’s accuracy and battery claims reflect its published testing; they do not establish a diagnosis or the same runtime for every activity.