Apple has unveiled its 2026 Apple Watch lineup, featuring the Apple Watch Ultra 4 and the Apple Watch Series 12. These models are powered by the new S11 chip, which is based on the A20 Pro chip from the iPhone 18 Pro. While the Ultra 4 appears visually identical to its predecessor, the Ultra 3, and the Series 12 is nearly identical to the Series 11, the upgrades represent one of the most significant updates in recent years. The new chip opens up new possibilities for the Apple Watch, particularly with upcoming watchOS updates that will enable exclusive features on the Ultra 4 and Series 12, which are the only models capable of handling complex tasks that involve continuous data analysis. The S11 chip is significantly faster and designed for future capabilities, with its central processing unit (CPU), graphics processing unit (GPU), and neural engine derived from the A20 Pro. Apple has also introduced specialized processors for background tasks and audio listening, allowing the main system to remain idle when not needed. This results in improved responsiveness, faster app performance, and quicker access to health and fitness data. The Apple Watch Ultra 4 offers battery life lasting more than two days, even during active use or sleep. A new 10 W charger can restore about half of the battery in just 15 minutes. Heart rate monitoring has also been greatly enhanced, now measuring heart rate every five seconds throughout the day, even while moving—60 times more frequently than before. This allows users to see their heart rate alongside the time on the watch face, with a new interface appearing instantly when opening the Heart Rate app. Apple has also improved its pedometer for greater accuracy and introduced heart rate variability (HRV), measured every five minutes at rest instead of every two hours. HRV is split into two categories: one for tracking daily stress and fatigue, and another for cardiovascular health. This feature is seen as a response to competing devices like Whoop and Bevel, which have made HRV a key indicator of recovery. The new Vital Signs app now replaces sleep duration with HRV, which could be controversial since sleep duration is a more familiar metric for the general public. Another new feature, the Readiness Index, assigns a score from 0 to 10 based on recent activity, sleep, and nightly health metrics, though it is still limited in usefulness due to a lack of detailed feedback or sport-specific recommendations.