Apple says the Apple Watch Series 12 “measures heart rate every five seconds, all day long”, with 60x more frequent background heart rate readings and 24x more frequent HRV readings than Series 11. What Apple publishes about the handling of all that data runs to two sentences: health and fitness data in the Health app, other than your Medical ID, is encrypted when the device is locked, and you decide what goes into the app and who can see it.
Those two sentences predate the Series 12. Apple published no new product-specific privacy notice with the new sensing system, and none with Labs, the $119 blood test it now sells through Quest Diagnostics.
Key facts: what the Series 12 collects and what Apple documents
| Item | What Apple publishes |
|---|---|
| Health Sensing System | Second-generation electrical heart sensor, always-on optical heart sensor, blood oxygen sensor, temperature sensor |
| Heart rate frequency | “Measures heart rate every five seconds, all day long” |
| Against Series 11 | “60x more frequent background heart rate readings” and “24x more frequent HRV readings” |
| Encryption | Health and fitness data in the Health app, other than Medical ID, “is encrypted” when the device is locked |
| Your control | “You decide what information is placed in the Health app as well as who can access your data” |
| Audio handling | Secure Exclave, “a dedicated hardware-isolated compartment”, and no audio recordings stored |
| Labs | $119 for “over 50 key biomarkers” at “approximately 2,000 Quest Diagnostics locations in the U.S.” |
| New privacy notice or retention period | Neither published |
| watchOS 27 | Monday, September 14, free |
The frequency claims, and what they are measured against
The frequency claims sit on the Series 12 product page and are given against Series 11 rather than as absolute rates. The five-second figure is from Apple’s September 9 announcement, and Apple gives no absolute rate for HRV, blood oxygen or temperature. Our Series 12 launch coverage has the hardware picture, and the Apple Watch Ultra 4 carries the same system.
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The two sentences Apple publishes about health data
On its privacy features page, Apple states that “all your health and fitness data in the Health app, other than your Medical ID, is encrypted” when the device is locked, and that “You decide what information is placed in the Health app as well as who can access your data”.
Read those precisely. The first is about data in the Health app, names one exception, and is tied to the device being locked. The second is about your controls, not about where data is processed.
The audio side is the one part with a named mechanism
For Audio Intelligence, Apple publishes more. Support document 148354, dated September 9, says the features use “the built-in microphone and secure S11 chip in Series 12, alongside the power of Apple Intelligence”, and describes the Secure Exclave on Apple Watch as a dedicated hardware-isolated compartment. Apple states that no audio recordings are stored.
That set is Sound Recognition, Music Recognition with Shazam, Live Rewind and Siri Recap. The first two are available now on Series 12 and Ultra 4. Live Rewind and Siri Recap are coming in beta late 2026, in English, in the U.S. first, and need iPhone 16 or newer. Apple says these features carry daily usage limits and that expanded access to such features will be available for a fee in the future.
Apple Intelligence runs on device and on servers through Private Cloud Compute, and Apple says it “analyzes whether it can be processed on the device or if it requires Private Cloud Compute” when a request is made. Apple publishes no per-feature map of which health or audio requests fall on which side of that line.
Labs, and the notice that did not change
Alongside watchOS 27, Apple announced Labs: $119 for over 50 key biomarkers at approximately 2,000 Quest Diagnostics locations in the U.S., with results surfacing in the Health app. The redesigned Health app is “later this year”, U.S. English first, as set out in our September 9 event recap.
No new or updated product-specific privacy notice accompanied either the Health Sensing System or Labs. The encryption language above is the same language Apple used before these products existed. The last-updated date on Apple’s own privacy policy page could not be read on a direct fetch, so we are not quoting one.
Apple does label the medical status and the eligibility of each feature, and those labels are published precisely.
| Feature | Apple’s published label |
|---|---|
| Vitals app | “For wellness purposes only and not for medical use” |
| Cycle Tracking | “Should not be used as a form of birth control” |
| ECG app | “Intended for use by people 22 years old or older” |
| Sleep apnea notifications | For people 18 or older “without a diagnosis of sleep apnea” |
| Hypertension notifications | Analyses optical heart sensor data over 30-day evaluation periods, and excludes anyone under 22, anyone pregnant and anyone already diagnosed |
Support document 117296 still does not name Series 12 or Ultra 4.
What Apple has not said
- No retention period for heart rate, HRV, blood oxygen, temperature or any other Health data.
- No statement covering Health data while the device is unlocked. The encryption sentence is about the locked state.
- No product-specific privacy notice for the Health Sensing System, Labs or the redesigned Health app.
- No statement about which health features use Private Cloud Compute and which stay on the watch or iPhone.
- No absolute sampling rate for HRV, blood oxygen or temperature.
watchOS 27 arrives Monday, September 14 as a free update, and Series 12 and Ultra 4 reach stores on Friday, September 18 alongside the iPhone 18 Pro. That week is the likeliest moment for a privacy notice to appear.
