Apple Watch Series 12 and Ultra 4 add redesigned heart sensors, AI audio recaps and ceramic case

What Apple announced

Apple used its September 9, 2026 "Surprise and shine" event to unveil the Apple Watch Series 12 and Apple Watch Ultra 4. According to The Verge, both watches launch on September 18, with preorders open immediately. Starting prices hold steady: the Series 12 begins at $399 in aluminum (space gray, black, light gold or dark bronze), rises to $699 in titanium (natural or radiant gold) and reaches $899 in the newly offered ceramic (night blue or pearl white). The Ultra 4 stays at $799 in natural or black titanium, alongside a premium Hermès edition.

A rebuilt heart-sensing system

The most consequential change sits under the display. Both watches carry a new Health Sensing System built on refreshed optical and electrical heart sensors, which The Verge describes as the first major update to this hardware in a while. Apple representatives pointed to a "32-petal" electrode design replacing the older two-petal layout, with the optical sensors moved closer together to reduce light leakage — in theory, enabling more accurate readings.

In practice, the watches take continuous background heart-rate measurements every five seconds, and Apple's press release claims higher-frequency heart-rate and heart-rate-variability sampling plus "the most accurate heart rate sensing in a wearable." That is Apple's own characterization rather than an independently tested result.

The new hardware also gates software features. A Readiness score — built from recent activity, training load, vitals and sleep — works only on the Series 12 and Ultra 4 because it depends on the new sensor array, The Verge notes. A redesigned Health app arriving later this year adds a Longevity tab with a Health Age metric that compares your health metrics against your chronological age.

Audio Intelligence reaches the wrist

The S11 chip, which Apple calls its most powerful wearable silicon, powers a set of Audio Intelligence features: Sound Recognition, Live Rewind and Siri Recap. As The Verge reports, the watches can recite audio transcriptions and summaries, aimed at helping users remember key moments from conversations and stay alert to important sounds. Apple says these features arrive later this year and are built with privacy, security and accessibility at the core. watchOS 27 also brings Apple Intelligence to Siri on the watch, adding personal-context understanding and broader world knowledge.

Battery, weight and the rest of the spec sheet

The Ultra 4 gets the bigger endurance bump: The Verge's spec comparison puts it at up to 50 hours of battery life, up from 42 hours on the Ultra 3, and 84 hours in low-power mode, while Apple says it can track outdoor workouts for up to 45 hours. The Series 12 is rated at up to 24 hours of everyday use and 10 hours during outdoor workouts, with fast charging that restores roughly 12 hours of use in 15 minutes.

The trade-off is heft. Every new model is slightly heavier than its predecessor: ceramic Series 12 units weigh 42.8 grams at 42mm and 52.9 grams at 46mm, and the heaviest Ultra 4 reaches 63.1 grams, up from 61.8. Otherwise the outlines are familiar — 42mm/46mm and 49mm case sizes, 64GB of storage, the same LTPO3 OLED panels at 2,000 nits for the Series and 3,000 nits for the Ultra, 50-meter versus 100-meter water resistance, and the Ultra keeping its siren, night mode, satellite SOS and 40-meter depth gauge.

Why it matters

Two threads stand out. First, the sensor overhaul shows where Apple believes the watch's value lies: not in new screens or cases alone, but in increasingly granular health data. Features like Readiness and Health Age push the device toward coaching and longevity positioning, putting it in more direct competition with Garmin, Oura and Whoop. Second, transcription and summary features running on a watch mark on-device AI reaching wearables — though because Apple is shipping them in a later software update, launch-day buyers get hardware whose headline AI features are not fully active yet. Holding starting prices while adding a ceramic option and new sensors keeps pressure on rivals, but Apple's accuracy claims will need independent testing before they can be taken at face value.