Apple’s new Watch Series 12 and Ultra 4, announced Wednesday and arriving September 18, center on a major overhaul of how the devices monitor your health throughout the day.
The changes go well beyond software tweaks, starting with a redesigned sensor architecture Apple is calling the Health Sensing System.
The most consequential upgrade for everyday users is a dramatic increase in heart rate monitoring frequency.
Where previous Apple Watch models checked heart rate at intervals, the Series 12 now measures it every five seconds, 60 times more often than before.
That continuous stream of data appears on a new watch face complication, giving users a live view of their heart rate throughout the day rather than periodic snapshots.
Heart rate variability, which Apple uses to assess recovery and overall cardiovascular health, is now sampled up to 24 times more frequently, with the Heart Rate app gaining a new section that separates recovery HRV from general HRV readings.
Redesigned Sensors and Smarter Step Tracking
The hardware behind these improvements includes a larger electrode surface area for better ECG skin contact, photodiodes arranged in a ring for more efficient light capture, and bigger green LEDs that Apple says maintain accuracy during movement.
The practical result is cleaner data during workouts and daily wear, particularly when your wrist is in motion.
Step tracking also gets a meaningful update. Apple rebuilt its pedometer using new machine learning algorithms, which the company says improves distance accuracy for indoor workouts and all-day step counts.
The S11 chip enables a real-time steps complication on the watch face, so users who rely on daily step goals can track progress without opening an app.
A new daytime vitals view lets users toggle between overnight and daytime readings in one place, which could surface health shifts that don’t appear until later overnight readings are analyzed.
VO2 Max Test and Battery Gains
A new VO2 max test uses the iPhone camera to watch users perform a series of exercises, then delivers results immediately alongside Apple Watch data.
VO2 max measures aerobic fitness, and Apple’s implementation differs from the passive estimation the watch has offered in previous years, instead running a structured test that produces an on-the-spot result.
Battery life improves as well. The Series 12 offers up to 10 hours during an outdoor workout, a 25% increase over its predecessor, and 15 minutes of charging adds up to 12 hours of use.
The Ultra 4 pushes further, rated at up to 50 hours of everyday battery life, 84 hours in Low Power Mode, and a new Max Extended Workout mode that Apple says can sustain up to 45 hours of continuous outdoor tracking. Fifteen minutes on the charger returns up to 18 hours of use.
The Apple Watch Series 12 starts at $399 and the Ultra 4 at $799. Pre-orders are open now, and both models will be available in stores beginning September 18.
