Apple has unveiled the Apple Watch Ultra 4, and while it might look familiar on the outside, there are some significant upgrades under the hood, particularly for athletes, endurance junkies and anyone who takes their health data seriously.
The new Ultra introduces Apple’s S11 chip and Health Sensing System, along with more accurate heart-rate and step tracking, a new Readiness score, significantly longer workout battery life and a new generation of Apple Intelligence features.
Here are the biggest changes:
1. Heart Rate Is Now Measured Every Five Seconds
One of the biggest upgrades is something you might not immediately see.
The Apple Watch Ultra 4 introduces Apple’s new Health Sensing System, featuring redesigned optical and electrical heart sensors. Apple says this delivers its most accurate heart-rate sensing yet, based on testing involving more than 1,000 participants.
More importantly, the watch now measures your heart rate every five seconds throughout the day, using larger, more power-efficient green LEDs.
That means more continuous data about how your body is responding throughout the day, not just when you’re working out.
2. HRV Tracking Gets Much More Serious
If you’re an athlete who already pays attention to heart rate variability (HRV) as an indicator of recovery and stress, this is a big one. The Ultra 4 can measure HRV up to 24 times more frequently than before.
Apple also separates HRV into two measurements: Recovery HRV, aimed at detecting day-to-day stress and recovery signals, and overall HRV, which provides a broader picture of health.
Recovery HRV is also incorporated into overnight Vitals and compared against your personal baseline, while a new daytime Vitals view lets you monitor changes that occur during the day.
3. Apple Finally Has a Readiness Score
Garmin, Oura and other fitness wearables have long tried to answer one question: How ready is my body to train today?
Apple now has its own answer.
The new Readiness feature combines recent activity, training load, vitals and sleep score to produce a daily score from 0 to 10.
Instead of just throwing a number at you, the Watch gives you one of four recommendations:
Recover. Pace Yourself. Ready. Go For It.
The score can also change throughout the day. Smash a brutal workout at lunchtime or experience a shift in your daytime vitals, for example, and your Readiness can update accordingly.
For athletes trying to balance training and recovery, this could arguably be one of the Ultra 4’s most useful additions.
4. Battery Life Goes Up to 50 Hours
Battery life has always mattered more on the Ultra than on a regular Apple Watch, and the Ultra 4 gets a meaningful boost.
For everyday use, Apple now claims:
Up to 50 hours of normal battery life
Up to 84 hours in Low Power Mode
Charging is faster too. A 15-minute charge can provide up to 18 additional hours of battery life. That should make the Ultra considerably easier to live with if you’re using it for sleep tracking as well as daily training.
5. It Can Track an Outdoor Workout for Up to 45 Hours
This is where things get particularly interesting for ultra-endurance athletes. The new Extended Workout mode provides up to 25 hours of workout tracking with full GPS and heart-rate readings – 25 percent more than the previous model.
Need even more?
Max Extended Workout mode stretches that to 45 hours for outdoor running, walking and hiking, while still taking GPS readings every second.
Apple says that’s typically enough battery life to complete a 100-mile race. For ultramarathons, multi-day hikes and other endurance events, that’s a substantial upgrade.
6. Step Tracking Has Been Completely Redesigned
Step counting doesn’t sound particularly exciting, until you realise how much fitness data depends on accurate movement tracking.
Apple says it has completely redesigned its pedometer model using new machine-learning algorithms and the S11 chip.
The result is more accurate step counting throughout the day and better distance measurements during indoor runs and walks. Apple claims the Ultra 4 now provides the most accurate step tracking of any smartwatch, based on its own testing against competing devices.
There’s also finally a dedicated Steps complication, allowing you to see your step count directly on the watch face.
7. Your Watch Can Now Help You Remember Conversations
This is probably the most futuristic addition. The S11 chip powers a new suite of Audio Intelligence features coming later this year.
Live Rewind lets you double-press the Digital Crown to see a text snippet of the previous 15 seconds of a conversation.
Siri Recap can generate a high-level summary and key points from conversations for you to review later.
Sound Recognition can alert users to important sounds such as sirens, alarms, doorbells or a baby crying.
And Shazam can automatically identify music playing around you and surface the song in the Smart Stack.
Apple says these features don’t create or store audio recordings. Audio processing takes place in a hardware-isolated Secure Exclave, with the raw audio deleted after processing. Live Rewind and Siri Recap will arrive in beta later in 2026.
8. Siri Gets Apple Intelligence on Your Wrist
With watchOS 27, the Ultra 4 also gets the new Siri AI powered by Apple Intelligence. That means Siri can use personal context as well as broader world knowledge, bringing more capable AI interactions directly to the Watch.
There’s even a new Siri Modular watch face designed around quicker access to Siri.
watchOS 27 adds a few other quality-of-life upgrades too, including a dynamic app grid, smarter Smart Stack suggestions and a new single-handed tap gesture that lets you select widgets by tapping your index finger and thumb.
So, Is the Apple Watch Ultra 4 a Big Upgrade?
The Ultra 4 isn’t about dramatically changing what an Apple Watch looks like. The bigger story is what it can now measure, understand and sustain.
For athletes, the combination of more frequent heart-rate and HRV measurements, Readiness, improved GPS and step tracking, and up to 45 hours of outdoor workout tracking makes the Ultra 4 considerably more focused on training and recovery.
For everyone else, longer everyday battery life and Apple’s new AI features arguably make it a more capable smartwatch beyond sport as well.
The Apple Watch Ultra 4 starts at S$1,199 in Singapore, with availability beginning 18 September 2026. It comes in natural and black titanium.
One Singapore-specific caveat: Hypertension Notifications will not initially be available here on the Ultra 4 while Apple awaits additional regulatory clearance, with availability expected next year.
