Apple Watch Ultra 4 lands with boosted battery life and revamped sensor

Apple's premium smartwatch gains a 50-hour battery estimate, recovery and longevity insights, and Siri AI

Apple has officially revealed the Apple Watch Ultra 4, updating its premium smartwatch line with extended battery life, more advanced biometric insights, and redesigned sensing architecture.

While retaining the same titanium silhouette as previous generations, the new S11 chip delivers up to 50 hours of everyday battery life, and the brand's overhauled 'Health Sensing System' is claimed to provide the most accurate heart rate monitoring of any wearable.

Revamped sensor and native Readiness insights

Under the hood, the Ultra 4's re-architected optical sensor hardware is the headline change between generations. It's the same setup as the Apple Watch Series 12, also announced at the brand's annual September showcase.

Larger green LEDs now capture continuous heart rate readings every five seconds and sample heart rate variability (HRV) 24 times more frequently. As with the Series 12, HRV is split into 'Recovery HRV' for daily stress monitoring and 'Overall HRV' for long-term cardiovascular health.

These metrics feed directly into the new native 'Readiness' engine. By evaluating overnight vitals, sleep scores, and recent training load, it delivers a daily score from 0 to 10 alongside actionable recommendations ranging from Recover to Go For It.

A new Daytime Vitals dashboard also lets wearers track biometric shifts throughout the day, while the redesigned Health app on iPhone (arriving later this year) includes a new Longevity tab. This includes a Health Age feature that shows how metrics track relative to a user’s age.

Big battery gains and step tracking precision

The standout upgrade for outdoor adventurers is the improved battery endurance. Standard usage increases to 50 hours (stretching to 84 hours in Low Power Mode), while fast charging adds 18 hours of battery life in just 15 minutes.

That's up from the Apple Watch Ultra 3, which was estimated to last up to 42 hours of normal use and up to 72 hours in Low Power Mode (though, as we point out in our extended review, we often got over 50 hours even without triggering Low Power Mode).

For continuous workout tracking, Extended Workout mode now delivers up to 25 hours with full GPS and heart rate logging. A Max Extended Workout mode pushes this to 45 hours—enough to cover a 100-mile ultramarathon with second-by-second GPS sampling.

Additionally, a revamped machine-learning-driven pedometer model claims to offer the most accurate step tracking on any smartwatch, paired with a new real-time Steps watch face complication.

Audio Intelligence and watchOS 27

The Ultra 4 also inherits Apple's new 'Audio Intelligence' suite, which, for those concerned with privacy, is processed in complete isolation via the S11 chip's hardware 'Secure Exclave'.

Features include Live Rewind (a crown double-tap to preview the last 15 seconds of spoken audio as text), Siri Recap for conversation summaries, and standalone Sound Recognition for emergency sirens and alerts. Apple says Siri Recap and Live Rewind arrive in beta later this year.

Running watchOS 27, the smartwatch also gains Siri AI, a new single-handed tap gesture (pinching index finger and thumb to select Smart Stack widgets), and a dynamic app grid that predicts a user's top five apps.

Finishes, pricing, and availability

The Ultra 4 remains available in the same 49mm Natural and Black titanium finishes as the previous two generations.

Band updates include new colors for the Trail Loop and Alpine Loop, translucent silicone Ocean Bands (in gray, kelp, and black), and a premium Hermès Grand H titanium band with an extension mechanism that adjusts over wetsuits.

It's available for pre-order today at $799 / £799—which represents a hold in the US and a £50 price increase in the UK—with general retail availability starting Friday, September 18th.