Apple has introduced Apple Watch Ultra 4 and Apple Watch Series 12, both built around a new Health Sensing System and Apple’s S11 chip. Pre-orders are open now in Singapore, with availability from 18 September.

Both watches use new optical and electrical heart sensors that measure heart rate every five seconds throughout the day, up from far less frequent readings on earlier models. Apple says this makes them the most accurate heart rate sensors in a wearable, based on a study of more than 1,000 participants comparing its sensing accuracy against other leading wearables. Heart rate variability, a marker of stress and recovery, is now measured up to 24 times more often.

“The new Health Sensing System and S11 chip take Apple Watch Ultra 4 — our most rugged and capable Apple Watch — to the next level, delivering longer battery life, faster charging, and the most accurate heart rate sensing in a wearable,” said Kaiann Drance, Apple’s vice president of Worldwide Apple Watch Product Marketing.

Readiness score and longer battery life on Ultra 4

Both watches introduce readiness, a daily 0-10 score derived from recent activity, training load, vitals and sleep, paired with one of four recommendations: Recover, Pace Yourself, Ready or Go For It. The score updates through the day as new data comes in.

Apple Watch Ultra 4 gets the bigger battery gains. Everyday use now stretches to up to 50 hours, or 84 hours in Low Power Mode, and a 15-minute charge adds up to 18 hours. For outdoor tracking, a new Max Extended Workout mode runs for up to 45 hours with GPS readings every second, enough for most 100-mile races. It starts at S$1,199 in natural or black titanium.

Series 12 adds Ceramic Shield 2 and more finishes

Apple Watch Series 12 starts at S$599 and comes in 42mm and 46mm sizes, with aluminium, titanium and ceramic case options. Aluminium models now use Ceramic Shield 2, which Apple says is 60 percent tougher than the glass on the previous generation. Battery life stays at up to 24 hours of everyday use and up to 10 hours during an outdoor workout, with a 15-minute charge now adding up to 12 hours.

Audio Intelligence listens without recording

Both watches gain a new set of Audio Intelligence features arriving later this year. Live Rewind replays the last 15 seconds of a conversation as a text snippet when a user double-presses the Digital Crown, and Siri Recap generates a short summary and key points afterwards. Sound Recognition alerts users who are deaf or hard of hearing to sounds like sirens, alarms or a crying baby, even without an iPhone nearby, and Shazam identifies music playing nearby from the Smart Stack.

Apple says none of this is recorded or stored. Audio is processed inside Secure Exclave, an isolated compartment on the S11 chip, then deleted immediately, and the features don’t identify who is speaking. Live Rewind plays an audible chime and shows an on-screen indicator whenever it’s active, so people nearby know it’s running. Siri Recap and Live Rewind launch in beta later this year and require an Apple Intelligence-enabled iPhone.

watchOS 27 and a Singapore gap on hypertension alerts

Both models ship with watchOS 27 and Siri AI, Apple’s overhauled assistant, rolling out in beta from 14 September. The update also adds a dynamic app grid of Siri-suggested apps, a single-handed tap gesture for the Smart Stack, and support for perimenopause and menopause tracking in Cycle Tracking.

One feature won’t be available locally at launch: Apple says Hypertension Notifications will not initially be offered in Singapore on either Series 12 or Ultra 4, pending additional regulatory clearance, with availability expected next year.