Apple introduced the Apple Watch Ultra 4, its top-tier sports watch, with 3 main new things: more accurate heart measurement, longer battery, and new AI features that help with sound and conversation. Pre-orders open today, on sale September 18, starting at US $799.
The most accurate heart rate measurement of any smartwatch
The Ultra 4 uses a new Health Sensing System together with the S11 chip, which means:
• It measures heart rate every 5 seconds, all day (previously measured at wider intervals)
• It measures HRV (Heart Rate Variability — the variation in your heartbeat's rhythm; the more variable this value, the better recovered your body usually is, while a low value tends to indicate stress or fatigue) up to 24x more often
• It splits HRV into 2 views: a "recovery" one (how well you've bounced back from fatigue) and an "overall" one (long-term heart health)
Apple says this is the most accurate heart measurement of any smartwatch, based on Apple's own internal testing with over 1,000 people, compared against other top-selling watch brands.
Readiness: a score telling you how ready your body is today
A new feature that combines your exercise data, training load, heart values, and sleep quality into a 0-10 score with a simple recommendation — whether today should be "rest," "ease in," "ready to go," or "go all out." This score also updates during the day, for example after a hard workout.
Longer battery, faster charging
• Up to 50 hours of typical use (previously more than 2 days)
• With low power mode on, up to 84 hours
• Just 15 minutes of charging gives up to 18 more hours of use
• Extended Workout mode, using GPS for location plus heart tracking, lasts up to 25 hours — up 25% from the previous generation
• Max Extended Workout mode lasts up to 45 hours — enough for a 100-mile ultramarathon (all these battery figures come from Apple's own testing; real-world use may differ by user habits)
More accurate step counting
The step-counting system has been completely rebuilt with AI, making step counts and distance more accurate when running or walking indoors, with a real-time step-count widget on the watch face.
A redesigned Health app on iPhone
The Health app gets a major overhaul later this year. What's new:
• A Longevity tab with a Health Age feature that tells you what "age" your health is right now, compared with your actual age
• Movement assessments — flexibility, strength, balance — using the iPhone camera together with heart data from the watch
• Book a lab test for 50+ health markers for $119 right through the app (at around 2,000 Quest Diagnostics locations in the US — this feature starts in the US first)
Audio Intelligence: AI features for sound
Using the watch's built-in microphone together with the S11 chip and Apple's AI models (some processing done on encrypted cloud, called Private Cloud Compute), there are 4 main features:
• Sound Recognition — alerts users who are hard of hearing or deaf when it hears an important sound, such as a siren, a fire alarm, a doorbell, or a baby crying, even without an iPhone nearby
• Live Rewind — double-press the Digital Crown to see a text summary of the last 15 seconds of what was just said, in case you missed it
• Siri Recap — summarizes the key points of a conversation to review later in the Siri app
• Shazam — listens to music around you and automatically shows the song/artist
On privacy: Apple states these features don't record or store audio files. The raw audio used for processing is completely inaccessible — not to the operating system, other apps, the user, or even Apple — because the S11 chip has a part called Secure Exclave, a separate processing area that deletes the audio immediately after processing. Users can turn each feature on/off themselves, and Live Rewind has an alert sound and a blinking light so people around you know it's in use. The feature doesn't distinguish who said what (no speaker identification), to protect the privacy of everyone in the conversation. Live Rewind and Siri Recap enter beta late this year, starting with English, and won't be available in EU countries at first.
A new version of Siri AI
Alongside watchOS 27, the watch supports a new version of Siri powered by Apple Intelligence, understanding the user's personal context better and answering a wider range of general questions. There's a separate Siri app for continuous conversation, plus a new watch face with easier access to Siri (English beta first, other languages to follow).
Other things in watchOS 27
• Pinch your index finger and thumb on one hand to open a widget without using your other hand
• Auto-suggested widgets based on your situation, like a parked-car location reminder or a friend's birthday reminder
• Support for tracking perimenopause and menopause in the Cycle Tracking app
• The Workout Buddy assistant works even without an iPhone nearby, and now supports Spanish in addition to English
Design, bands, and environment
Two colors: natural titanium and black titanium, with several new band colors. The body is made of 45% recycled material, including 100% recycled titanium, and uses renewable electricity throughout manufacturing.
Price and release date
• US price from $799
• Thai price from 29,900 THB (49 mm titanium case, comes with GPS + Cellular as standard)
• The new bands can be ordered today via apple.com/th/store; the Thai release date for the watch itself isn't confirmed yet (in the US, on sale September 18, 2026)
• watchOS 27 rolls out September 14, 2026, for Apple Watch Series 9 and up, SE 3, and Ultra 2 and up (must be paired with an iPhone 11 or newer running iOS 27)
