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Apple has introduced the Apple Watch Series 12 and Apple Watch Ultra 4, its latest smartwatch models for 2026. Rather than making major changes to the overall design, Apple has focused this generation on health sensing, processing performance, software features, charging, and battery life.
Both models feature Apple’s new Health Sensing System, the S11 chip, more frequent heart-rate and heart-rate variability (HRV) measurements, and a new Readiness experience. The Ultra 4 also offers a substantially longer battery rating than the standard Apple Watch Series 12.
Apple Watch Series 12 Retains the Familiar Design
The Apple Watch Series 12 maintains the familiar Apple Watch design, with most of the changes taking place internally.
The Series 12 is available in aluminum, titanium, and ceramic configurations, with different finishes offered across the materials. Ceramic returns to the Apple Watch lineup in Pearl White and Night Blue.
The Apple Watch Ultra 4 also keeps the overall design of the previous Ultra generation and continues to use a titanium case. Its updates are mainly focused on health sensing, processing, battery performance, and software.
New Health Sensing System
One of the main changes in the new Apple Watch Series generation is Apple’s Health Sensing System.
The system includes redesigned photodiodes, larger green LEDs, and a larger electrode surface designed to improve sensor contact. Apple says the new system allows the watches to collect heart-rate information more frequently.
Apple also claims that the new system provides its most accurate heart-rate sensing in a wearable. This is based on Apple’s own testing and a study involving more than 1,000 participants, so it should be regarded as an Apple-reported claim rather than an independent industry-wide ranking.
More Frequent Heart-Rate and HRV Measurements
The Apple Watch Series 12 and Ultra 4 can measure heart rate every five seconds throughout the day, according to Apple.
The watches also support more frequent heart-rate variability measurements. The additional HRV information feeds into features such as Vitals and Readiness, giving users more data about changes in their measurements over time.
These measurements are intended for health and fitness insights and should not be considered a replacement for professional medical evaluation.
New Readiness Experience
Apple is also introducing a Readiness experience for the new Apple Watch models.
The feature uses information such as sleep, activity, and health measurements to provide an indication of how prepared a user may be for activity.
The feature requires sufficient data before producing a result. Early reviews noted that reviewers needed to use the watch for a period of time before they could fully assess the feature.
Readiness is designed as a wellness and fitness feature rather than a medical diagnosis or clinical assessment.
S11 Chip Powers the New Models
Both the Apple Watch Series 12 and Apple Watch Ultra 4 are powered by Apple’s S11 chip.
The processor supports the updated health features and other watchOS functions. Initial reviews have also reported improvements in areas such as Siri responsiveness and general interaction with the watch.
The S11 chip also provides the processing platform for upcoming Audio Intelligence capabilities that Apple plans to introduce through software updates.
Battery Life and Charging
Battery performance is another significant difference between the two models.
| Feature | Apple Watch Series 12 | Apple Watch Ultra 4 |
| Normal battery rating | Up to 24 hours | Up to 50 hours |
| Health Sensing System | Yes | Yes |
| S11 chip | Yes | Yes |
| Readiness | Yes | Yes |
| Higher-frequency HRV | Yes | Yes |
| Case materials | Aluminum, titanium, ceramic | Titanium |
The Apple Watch Series 12 is rated for up to 24 hours of normal use. Apple has also improved charging, allowing users to gain several additional hours of use from relatively short charging periods.
The Apple Watch Ultra 4 is rated for up to 50 hours of normal use, giving it considerably more battery endurance than the standard model.
Actual battery life can vary depending on factors such as workouts, cellular connectivity, display usage, and health-tracking activity.
Improved Step Tracking
The Apple Watch Series 12 also receives changes to step and distance tracking.
Apple says updated machine-learning algorithms can improve distance measurements during indoor walking and running workouts. A new Steps complication also allows users to view their step count directly from the watch face.
Apple’s accuracy statements are based on its own testing and should not be interpreted as an independent comparison with every competing smartwatch.
Audio Intelligence Features Are Still Coming
Apple has announced additional Audio Intelligence capabilities for the new Apple Watch models.
These features are intended to provide new ways of interacting with information captured through the watch. However, some of the announced capabilities were not available for reviewers to fully test during the initial review period.
As a result, their real-world performance and usefulness cannot yet be assessed from the initial reviews. More information should become available as Apple rolls out the relevant software updates.
Apple Watch Series 12 vs Ultra 4
The Apple Watch Series 12 and Ultra 4 share several important technologies, including the S11 chip, Health Sensing System, higher-frequency health measurements, and Readiness.
The main differences are their physical design and battery capacity. The Series 12 offers aluminum, titanium, and ceramic options, while the Ultra 4 retains its larger titanium design and provides substantially longer battery endurance.
The Ultra 4 is also designed around Apple’s more rugged, outdoor-oriented Apple Watch Ultra platform.
Conclusion
The Apple Watch Series 12 and Apple Watch Ultra 4 focus on internal improvements rather than a major visual redesign.
The new Health Sensing System enables more frequent heart-rate and HRV measurements, while the S11 chip supports the latest health and software capabilities. The Series 12 also introduces updated step tracking and faster charging, while the Ultra 4 offers significantly longer battery life.
Some announced software features are still rolling out, meaning the complete experience will become clearer as Apple makes those capabilities available. For now, the new Apple Watch Series models represent Apple’s latest move toward combining smartwatch functions with more detailed health and fitness tracking.