Apple announced the Watch Series 12 and Ultra 4 today. Both include a new “Health Sensing System” and S11 chip that give the devices the “most accurate heart rate sensing in a wearable,” Apple claimed during its fall event.
Apple’s depiction of the S11 chip.Credit:
Apple
Credit:
Apple
Both watches will use the new S11 chip alongside the new “Health Sensing System,” allowing the watches to deliver higher-frequency heart rate and heart rate variability (HRV) measurements than prior Apple Watches.
The Watch Series 12 and Ultra 4 (pictured) will run watchOS 27.The Health Sensing System includes redesigned photodiodes organized in a ring to capture light more efficiently and a larger electrode surface area for better skin contact. Additionally, the green LEDs on each Watch’s optical heart sensor are supposed to be bigger and more power-efficient and measure the user’s heart rate every five seconds. Users will be able to view their heart rate in real time with a new heart rate watch face special feature (also known as a complication).
The new watches can take HRV measurements up to 24 times more frequently than their predecessors, Apple said. HRV is an indicator of how well the body is able to adapt to changes such as stress and exercise.
“Overnight vitals now includes recovery HRV measurements analyzed against a user’s personal baseline, providing a more complete view of their health status. A new daytime vitals view lets users toggle between overnight and daytime metrics, and can potentially spot shifts in their metrics before they show up overnight,” Apple said in a press release.
Apple claims that the new wearables have the most accurate heart rate sensing in any wearable based on a study “on a diverse population of over 1,000 participants.”

The Watch Series 12 has an optional ceramic finish in midnight blue (top) and and pearl white (bottom).
Apple
The Watch Series 12 has an optional ceramic finish in midnight blue (top) and and pearl white (bottom).Apple

There are also titanium finishes (pictured) and aluminium finishes. The aluminum versions are supposed to be 60 percent “tougher” than prior aluminum models, per Apple.
Apple
There are also titanium finishes (pictured) and aluminium finishes. The aluminum versions are supposed to be 60 percent “tougher” than prior aluminum models, per Apple.Apple
The Watch Series 12 has an optional ceramic finish in midnight blue (top) and and pearl white (bottom).Apple
There are also titanium finishes (pictured) and aluminium finishes. The aluminum versions are supposed to be 60 percent “tougher” than prior aluminum models, per Apple.Apple
The new Watches will also introduce “readiness” scores, which Apple says “analyze a user’s recent activity, training load, vitals, and sleep score to offer insight into their capacity for the day ahead” on a scale from 0 to 10. This score updates throughout the day based on the user’s activity.
Apple will update the iOS Health app later this year, allowing Watch Series 12 and Ultra 4 users to access a new “Health Age” score.
“The Health app also includes movement evaluations that measure flexibility, strength, balance, and more using vision-based AI models on iPhone and heart rate data from Apple Watch. Users will be able to schedule and purchase new labs that feature over 50 key biomarkers for $119 directly through the Health app at approximately 2,000 Quest Diagnostics locations in the US,” Apple said.
Apple Intelligence features
The Watch Ultra 4 comes in “natural” and “black titanium” colorways.Credit:
Apple
Credit:
Apple
Apple is also incorporating more Apple Intelligence-based features into the new watches. These features include the ability to use the Shazam song detection feature, Live Rewind, which Apple said “shows the previous 15 seconds of a conversation as a text snippet” when users double-press the Digital Crown, and Siri Recap, which, per Apple, “can create high-level summaries of conversations that users can review later to jog their memory.”
Both watches are available for preorder today and will ship on September 18. The Watch Series 12 starts at $399, and the Ultra 4 starts at $799.
Scharon HardingSenior Technology Reporter
Scharon HardingSenior Technology Reporter
Scharon is a Senior Technology Reporter at Ars Technica writing news, reviews, and analysis on consumer gadgets and services. She’s been reporting on technology for over 10 years, with bylines at Tom’s Hardware, Channelnomics, and CRN UK.
