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Apple released watchOS 11.6.1 on August 14, 2025. Its headline change is a new Blood Oxygen experience for eligible Apple Watch owners in the United States: the paired iPhone calculates measurements, and results appear in the iPhone’s Health app. The feature is limited to Series 9, Series 10, and Ultra 2; this is not a broad new-feature update for every compatible watch.
What’s new in watchOS 11.6.1?
Apple describes the release’s notable change as a “new Blood Oxygen experience” for U.S. users with Apple Watch Series 9, Series 10, or Ultra 2. The watch collects the relevant measurement, the paired iPhone calculates it, and the result is viewed in Health on that iPhone. Apple does not document a new watch face, workout feature, or broader interface change for this release. Apple’s watchOS 11 update notes describe the feature and its scope.
That wording matters: this is not a universal return of the former on-watch Blood Oxygen experience. The calculation happens on the iPhone, and the published destination for results is Health.
Which Apple Watches are eligible?
General compatibility with watchOS 11.6.1 is broader than eligibility for the Blood Oxygen experience. Apple’s security-release listing identifies the update for Apple Watch Series 6 and later, while its Blood Oxygen description names only three models and limits the experience to the United States.
#1 Best Overall
![Apple Watch Series 11 [GPS 46mm] Smartwatch with Jet Black Aluminum Case with Black Sport Band - M/L. Sleep Score, Fitness Tracker, Health Monitoring, Always-On Display, Water Resistant](https://m.media-amazon.com/images/I/416RQ0rtsUL._SL160_.jpg)
- A FULL-FEATURED HEALTH TRACKER—Apple Watch Series 11 gives you invaluable insights about your body, right from your wrist. Take an ECG anytime* and get alerts for a high and low heart rate or an irregular rhythm*—so you can stay closer to your heart. You can also view your overnight health tracking metrics with the Vitals app* and be notified of possible sleep apnea.*
- KNOW YOUR SLEEP SCORE—With advanced sleep tracking, Series 11 gives you a daily sleep score. It’s an easy way to help measure and understand the quality of your sleep, so you can make it more restorative.
- GET HYPERTENSION NOTIFICATIONS—Did you know that Series 11 can spot signs of chronic high blood pressure? By analyzing how your blood vessels respond to beats of the heart, it can notify you of possible hypertension.*
- SAFETY FEATURES—A smartwatch that puts your safety first. Series 11 can detect a hard fall or severe car crash, automatically help connect you with emergency services, and notify your emergency contacts.* Check In can automatically notify a loved one when you’ve arrived at your destination.
- A POWERFUL FITNESS TRACKER—With advanced metrics and motivating features like Pacer, Heart Rate Zones, training load, and Workout Buddy powered by Apple Intelligence from your nearby iPhone*—Series 11 is made to help everyone stay active, from runners and hikers to strength-training enthusiasts.
| Watch model or group | watchOS 11.6.1 compatibility | U.S. Blood Oxygen experience described by Apple |
|---|---|---|
| Series 9 | Yes | Yes |
| Series 10 | Yes | Yes |
| Ultra 2 | Yes | Yes |
| Series 6–8, original Ultra, and SE models | Series 6 and later are within the update’s stated compatibility range | Not identified for this experience |
Feature availability can vary by device and region; watchOS compatibility alone does not establish Blood Oxygen eligibility. Apple’s watchOS 11 announcement also cautions that not all features are available on every device or in every region. If you have an imported or used watch, verify its exact model and regional history rather than assuming that its software version guarantees the feature.
How to install watchOS 11.6.1
Apple’s update instructions require the watch to have at least 50% charge. Keep the iPhone connected to Wi‑Fi and near the watch, and leave the watch on its charger during installation. Apple says installation can take several minutes to an hour; do not restart either device or quit the Apple Watch app while it is in progress. Follow the update prompt on the paired iPhone if one appears. The release was issued alongside iOS 18.6.1, but Apple’s public documentation does not make that iPhone update an unconditional requirement for every pairing.
Rank #2
![Apple Watch Series 11 [GPS 42mm] Smartwatch with Rose Gold Aluminum Case with Light Blush Sport Band - S/M. Sleep Score, Fitness Tracker, Health Monitoring, Always-On Display, Water Resistant](https://m.media-amazon.com/images/I/31caPPnRysL._SL160_.jpg)
- A FULL-FEATURED HEALTH TRACKER—Apple Watch Series 11 gives you invaluable insights about your body, right from your wrist. Take an ECG anytime* and get alerts for a high and low heart rate or an irregular rhythm*—so you can stay closer to your heart. You can also view your overnight health tracking metrics with the Vitals app* and be notified of possible sleep apnea.*
- KNOW YOUR SLEEP SCORE—With advanced sleep tracking, Series 11 gives you a daily sleep score. It’s an easy way to help measure and understand the quality of your sleep, so you can make it more restorative.
- GET HYPERTENSION NOTIFICATIONS—Did you know that Series 11 can spot signs of chronic high blood pressure? By analyzing how your blood vessels respond to beats of the heart, it can notify you of possible hypertension.*
- SAFETY FEATURES—A smartwatch that puts your safety first. Series 11 can detect a hard fall or severe car crash, automatically help connect you with emergency services, and notify your emergency contacts.* Check In can automatically notify a loved one when you’ve arrived at your destination.
- A POWERFUL FITNESS TRACKER—With advanced metrics and motivating features like Pacer, Heart Rate Zones, training load, and Workout Buddy powered by Apple Intelligence from your nearby iPhone*—Series 11 is made to help everyone stay active, from runners and hikers to strength-training enthusiasts.
Install from the paired iPhone
- If the iPhone offers a software update, install it as prompted.
- Place the Apple Watch on its charger and make sure it is at least 50% charged. Connect the iPhone to Wi‑Fi and keep it near the watch.
- On the iPhone, open Apple Watch and tap My Watch > General > Software Update.
- Download and install the update, entering a passcode if requested. Keep the watch on its charger until it restarts and completes installation.
Install directly on the watch
- Connect the Apple Watch to Wi‑Fi and place it on its charger.
- On the watch, open Settings > General > Software Update.
- Tap Install if the update is offered, then leave the watch on its charger until the process finishes.
For the general watchOS 11 generation, Apple lists an iPhone XS or later running iOS 18 as the iPhone requirement. The exact prompt can depend on the software already installed on the paired devices. See Apple’s watchOS 11 compatibility details and Apple’s Apple Watch update guide.
Where to find Blood Oxygen results
Open the Health app on the paired iPhone and use its search or browsing controls to locate Blood Oxygen. Apple identifies Health as the place to view results, but does not establish one permanent tap-by-tap path for every iOS version. Do not expect the result to be presented as the same direct on-watch reading you may remember from an earlier experience.
Rank #3
![Apple Watch SE 3 [GPS 40mm] Smartwatch with Starlight Aluminum Case with Starlight Sport Band - S/M. Fitness and Sleep Trackers, Heart Rate Monitor, Always-On Display, Water Resistant](https://m.media-amazon.com/images/I/31YiTby0pOL._SL160_.jpg)
- GET SMARTER HEALTH INSIGHTS—Apple Watch SE 3 is an advanced health tracker that helps you better understand your body. The smartwatch sends alerts for an irregular heart rhythm, or an unusually high or low heart rate.* You can view your overnight health tracking metrics with the Vitals app,* track your sleep score, and get sleep apnea notifications.*
- A GREAT FITNESS TRACKER—SE 3 can track your workouts in a healthy number of ways—from running and strength training to simply achieving your 10K steps a day. With real-time metrics and Workout Buddy powered by Apple Intelligence from your nearby iPhone,* you’ll hit your goals like never before.
- KEEP HELP CLOSE AT HAND—SE 3 is a smartwatch that can detect a hard fall or severe car crash and automatically help connect you to emergency services and notify your emergency contacts.* Check In can automatically notify a loved one when you’ve arrived at your destination.
- WOMEN’S HEALTH INSIGHTS—SE 3 has advanced sensors that track your wrist temperature while you sleep. With this smartwatch, you can log your periods and symptoms, get period predictions, and get notified of cycle deviations.*
- GREAT BATTERY LIFE AND FASTER CHARGING—Enjoy a smartwatch with all-day, 18-hour battery life* from sunup to sundown. Then charge up to twice as fast as SE 2* and get up to 8 hours of battery in just 15 minutes.*
If the Blood Oxygen category or data is missing
- Check that the watch is a U.S.-eligible Series 9, Series 10, or Ultra 2, and consider whether it was purchased or configured for another region.
- Confirm the watch completed the update and restarted; update the paired iPhone if prompted.
- Make sure the watch remains paired to the iPhone where you are checking Health data, then search Health for “Blood Oxygen.”
- Check that Health permissions and data sharing have not been restricted, then restart both devices.
- If it remains unavailable, contact Apple Support. Reinstalling watchOS cannot change hardware or regional eligibility.
If the software update itself will not start, Apple recommends checking the charger connection, restarting the watch and iPhone, and trying again. If a downloaded update file is stuck, open the iPhone’s Apple Watch app and go to General > Storage, delete the update file, then check for the update again. Users with beta software may need to remove the beta profile and restart both devices. Apple’s full update troubleshooting instructions cover these steps.
Should you install it or buy a different watch?
If you own a U.S. Series 9, Series 10, or Ultra 2 and want this Blood Oxygen workflow, installing the update is the direct next step; buying another watch is not necessary just to access the change. Owners of other compatible models should not expect a separately documented headline feature from this release. Apple does not publish a longer feature list for watchOS 11.6.1, so it is not accurate to promise general performance, battery, or bug-fix improvements.
Rank #4
![Apple Watch SE 3 [GPS 40mm] Smartwatch with Midnight Aluminum Case with Midnight Sport Band - S/M. Fitness and Sleep Trackers, Heart Rate Monitor, Always-On Display, Water Resistant](https://m.media-amazon.com/images/I/31Gq8SToFJL._SL160_.jpg)
- GET SMARTER HEALTH INSIGHTS—Apple Watch SE 3 is an advanced health tracker that helps you better understand your body. The smartwatch sends alerts for an irregular heart rhythm, or an unusually high or low heart rate.* You can view your overnight health tracking metrics with the Vitals app,* track your sleep score, and get sleep apnea notifications.*
- A GREAT FITNESS TRACKER—SE 3 can track your workouts in a healthy number of ways—from running and strength training to simply achieving your 10K steps a day. With real-time metrics and Workout Buddy powered by Apple Intelligence from your nearby iPhone,* you’ll hit your goals like never before.
- KEEP HELP CLOSE AT HAND—SE 3 is a smartwatch that can detect a hard fall or severe car crash and automatically help connect you to emergency services and notify your emergency contacts.* Check In can automatically notify a loved one when you’ve arrived at your destination.
- WOMEN’S HEALTH INSIGHTS—SE 3 has advanced sensors that track your wrist temperature while you sleep. With this smartwatch, you can log your periods and symptoms, get period predictions, and get notified of cycle deviations.*
- GREAT BATTERY LIFE AND FASTER CHARGING—Enjoy a smartwatch with all-day, 18-hour battery life* from sunup to sundown. Then charge up to twice as fast as SE 2* and get up to 8 hours of battery in just 15 minutes.*
If Blood Oxygen is your reason for considering a used or refurbished watch, check the exact model and regional history with the seller before buying. Do not treat watchOS 11 compatibility as proof that the Blood Oxygen experience will be available on a particular device.
Release date, security listing, and current-version context
watchOS 11.6.1 is a minor follow-up to watchOS 11.6, released August 14, 2025, for Apple Watch Series 6 and later. Apple’s security-release page lists no published CVE entries for this update; that means no CVEs are listed there, not that Apple has made a broader claim about every possible security change. Apple’s security releases page lists watchOS 26.6 as the latest version as of August 16, 2026, so 11.6.1 is not the current watchOS release.
Quick Recap
Best Value
![Apple Watch Series 11 [GPS 42mm] Smartwatch with Jet Black Aluminum Case with Black Sport Band - S/M. Sleep Score, Fitness Tracker, Health Monitoring, Always-On Display, Water Resistant](https://m.media-amazon.com/images/I/41s72HIk5TL._SL160_.jpg)
- A FULL-FEATURED HEALTH TRACKER—Apple Watch Series 11 gives you invaluable insights about your body, right from your wrist. Take an ECG anytime* and get alerts for a high and low heart rate or an irregular rhythm*—so you can stay closer to your heart. You can also view your overnight health tracking metrics with the Vitals app* and be notified of possible sleep apnea.*
- KNOW YOUR SLEEP SCORE—With advanced sleep tracking, Series 11 gives you a daily sleep score. It’s an easy way to help measure and understand the quality of your sleep, so you can make it more restorative.
- GET HYPERTENSION NOTIFICATIONS—Did you know that Series 11 can spot signs of chronic high blood pressure? By analyzing how your blood vessels respond to beats of the heart, it can notify you of possible hypertension.*
- SAFETY FEATURES—A smartwatch that puts your safety first. Series 11 can detect a hard fall or severe car crash, automatically help connect you with emergency services, and notify your emergency contacts.* Check In can automatically notify a loved one when you’ve arrived at your destination.
- A POWERFUL FITNESS TRACKER—With advanced metrics and motivating features like Pacer, Heart Rate Zones, training load, and Workout Buddy powered by Apple Intelligence from your nearby iPhone*—Series 11 is made to help everyone stay active, from runners and hikers to strength-training enthusiasts.
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