Apple Unveils Apple Watch Series 12 With All-New Health Sensing System

Apple has refreshed its smartwatch line with the Apple Watch Series 12. The defining change this year is the new Health Sensing System paired with the S11 chip, which together sample heart rate and heart rate variability far more often than before. That stream of data feeds a new readiness score, and the watch also gains a separate class of Apple Intelligence features built around sound. Apple says the updated system delivers the most accurate heart rate sensing available in a wearable.

Heart rate every five seconds and far more frequent HRV readings

The Health Sensing System combines redesigned optical and electrical heart sensors. Larger, more power-efficient green LEDs allow the watch to take a heart rate reading every five seconds throughout the day without the user starting a measurement manually. Because the data is collected continuously, the Move and Exercise rings become more accurate, and a new complication puts the current reading on the watch face.

Heart rate variability is now measured up to 24 times more often and has its own section in the Heart Rate app. Apple splits the metric in two: recovery HRV tracks the daily balance between stress and recovery, while overall HRV is meant for a longer view of cardiovascular health.

Overnight vitals now include recovery HRV measured against the user's personal baseline. A daytime view has been added as well, so switching between night and day metrics can reveal a shift before it shows up during sleep.

The pedometer model has also been rebuilt. Machine learning improves distance estimates during indoor workouts, and the S11 chip sharpens step counting through the day, which Apple claims makes this the most accurate step tracking on any smartwatch. Step totals are now available on the watch face in real time as well.

A readiness score for the day ahead

Readiness looks at recent activity, training load, vitals and the sleep score, then returns a single value from 0 to 10 alongside one of four recommendations: Recover, Pace Yourself, Ready or Go For It. Until now this was territory largely occupied by rival fitness bands.

The score is recalculated during the day, so a hard workout or a change in daytime vitals is reflected immediately, and the watch shows which factors moved the number. The algorithm was built on data from the Apple Heart and Movement Study together with exercise scientists and physicians at Apple.

Audio Intelligence: making sense of the sound around the user

A separate set of Apple Intelligence features draws on the built-in microphone, the processing power of the S11 chip, models running on iPhone and the Private Cloud Compute infrastructure. The goal is to keep users aware of important sounds and help them recall details from conversations.

Live Rewind shows a text snippet of the last 15 seconds of a conversation after a double press of the Digital Crown. The snippet can be queried through Siri or saved in the Siri app.

Siri Recap produces a short summary of a conversation with a title and key points. It can be switched on and off from Control Center and never generates a full transcript.

Sound Recognition alerts users to sirens, alarms, a doorbell or a crying baby. Detection runs on the watch itself, so an iPhone nearby is not required.

Faster music recognition through Shazam belongs to the same group: the track title and artist appear automatically in the Smart Stack widget.

The speech-related features are opt-in. No audio recordings are created or stored, because the S11 chip includes Secure Exclave, an isolated hardware compartment that processes sound apart from the rest of the system and deletes it immediately. Live Rewind plays a chime even when the watch is silenced and displays a microphone indicator so that people nearby can tell the feature is running. Snippets and summaries are stored with end-to-end encryption. Live Rewind and Siri Recap arrive in beta later this year.

watchOS 27, Siri AI and the redesigned Health app

The Series 12 ships with watchOS 27 and support for Siri AI, a version of the assistant that understands personal context and answers questions about the wider world, with a Siri Modular watch face for quick access. The release also brings a dynamic app grid with five Siri-suggested apps, a single tap gesture for picking a widget in the Smart Stack, perimenopause and menopause support in Cycle Tracking, and Workout Buddy without an iPhone nearby.

The Health app on iPhone has been reworked around two new tabs: Insights, which surfaces current metrics, and Longevity, which analyses long-term data. Longevity includes Health Age, a comparison of the user's metrics against their actual age. In the US, the app will also let users book lab work covering more than 50 biomarkers for $119. The redesign arrives later this year, starting in US English.

Battery life and charging

Everyday battery life stays at up to 24 hours. The bigger change is workout endurance, now rated at up to 10 hours of outdoor training, 25 percent more than the previous model. Charging is quicker too: 15 minutes on the charger provides up to 12 hours of use, half as much again as before.

Cases, materials and bands

The watch is still offered in 42mm and 46mm sizes. Aluminium versions come in the new dark bronze, black and light gold finishes alongside space gray, and their glass has been replaced with Ceramic Shield 2, which Apple says is 60 percent tougher than the Ion-X used on the Series 11. Titanium cases are available in natural titanium and a new radiant gold, while the ceramic version comes in pearl white and night blue.

The band line-up has grown as well. Sport Band gains new colours, Sport Loop introduces an inkjet-printed plaid pattern, Modern Buckle moves to a woven material and is offered with gold hardware for the first time, and Milanese Loop arrives in radiant gold and dark bronze. The Apple Watch Hermès Series 12 collection is available in radiant gold titanium for the first time and adds the Rocabar Club band.

Specifications

• Case sizes: 42mm and 46mm
• Chip: Apple S11
• Sensors: Health Sensing System with new optical and electrical heart sensors
• Heart rate sampling: every 5 seconds throughout the day
• Case materials: aluminium with Ceramic Shield 2, titanium, ceramic
• Battery life: up to 24 hours of everyday use, up to 10 hours of outdoor workouts
• Charging: 15 minutes for up to 12 hours of use
• Operating system: watchOS 27
• AI features: Apple Intelligence, Siri AI, Audio Intelligence
• Colour: aluminium in dark bronze, black, light gold, space gray; titanium in radiant gold, natural titanium; ceramic in pearl white, night blue