The Apple Watch Ultra 4 is a capable smartwatch that extends battery life and adds more insightful training and health features. The device retains the same 49mm grade 5 titanium case, physical buttons, and strap options as its predecessor, with only a negligible weight increase that users won’t notice day-to-day. A new health sensing system on the underside features larger electrodes and LEDs that monitor metrics like heart rate more frequently.
The watch runs on Apple’s new S11 chip and watchOS 27, powering a more advanced Siri that handles conversations beyond simple queries. The headline feature is the new Health Sensing System, which samples heart rate at a higher frequency to enable more accurate tracking and new features. In testing, the Ultra 4 performed well against a chest strap monitor, with similar average readings, though it slightly underreported maximum heart rate.
New Readiness scores require seven nights of sleep data alongside other metrics like heart rate variability, respiratory rate, and wrist temperature, and they dynamically adjust during the day based on activity. These features have been available on rival smartwatches for some time, but they are nicely presented on the watch. Vitals tracking now offers daytime and nighttime views of heart rate, HRV, and temperature changes, though it is not as glanceable as the Readiness scores.
Step count tracking is described as typically within a few hundred steps of other trackers, and GPS performance during a half marathon test was strong even on a twisty course. Battery life has improved from 42 hours on the Ultra 2 to 50 hours on the Ultra 4, giving users over two days of regular use. Fast charging provides up to 80% battery from a 45-minute charge, or enough for a night’s sleep tracking from a five-minute charge.
The Apple Watch Ultra 4 is Apple’s most capable smartwatch yet, combining longer battery life with more detailed health and training insights and promising Audio Intelligence features. However, the familiar design and limited availability of some headline features make it a modest upgrade over the Ultra 3, especially given its premium price of £749.
