Apple released iOS 18.6.1 and watchOS 11.6.1 on August 14, 2025, restoring Blood Oxygen measurements for certain U.S.-sold Apple Watch Series 9, Series 10, and Ultra 2 units that shipped with the feature disabled. The important catch is that the watch collects the sensor data, while the paired iPhone calculates and displays the result in Health → Browse → Respiratory → Blood Oxygen. This is not a return to the original, fully on-watch experience.
What Apple released
The enabling releases were iOS 18.6.1 for the paired iPhone and watchOS 11.6.1 for the affected watch. Apple announced them on August 14, 2025, saying the redesigned Blood Oxygen feature was enabled by a recent U.S. Customs ruling. These versions are the historical releases that restored the capability; they are not necessarily the latest software versions now. Apple’s security-release list shows iOS 18.6.2 on August 20, 2025 (Apple Support).
Apple’s announcement is available at Apple Newsroom. The updates themselves are free.
Which Apple Watches qualify?
Model name alone is not enough. Apple’s restoration applies to a narrow combination of model, sales region, and previous feature state.
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![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.
| Requirement | What must be true |
|---|---|
| Model | Apple Watch Series 9, Series 10, or Apple Watch Ultra 2 |
| Region | The watch is a U.S.-sold unit |
| Prior feature state | That specific watch currently lacks Blood Oxygen because it was sold with the feature disabled |
| Software | The paired iPhone and watch have the required compatible software |
- A Series 9, Series 10, or Ultra 2 that already had the original Blood Oxygen feature does not change.
- Watches purchased outside the United States were not part of this U.S. restoration.
- Other Apple Watch models were not named by Apple as eligible for this release.
Before troubleshooting, check the watch’s exact model and purchase region. An imported watch and a U.S. unit with the same retail name can have different feature histories.
Why Blood Oxygen was disabled in the United States
Apple disabled Blood Oxygen on affected U.S. models after a patent dispute involving Masimo and a U.S. International Trade Commission ruling. Reporting at the time connected the restriction to that case. Apple said the 2025 software release followed a recent U.S. Customs ruling that enabled its redesigned approach. Neither Apple’s announcement nor the update should be read as proof that every related patent dispute or litigation issue has permanently ended.
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.
For the release-day legal and software context, see MacRumors’ report.
How the redesigned Blood Oxygen feature works
- The optical sensor on the Apple Watch records the underlying data.
- The paired iPhone performs the measurement calculation.
- The result is saved and viewed in the iPhone Health app’s Respiratory section.
That division is the central difference from the original implementation. On an affected U.S. watch, you should not expect the old Blood Oxygen app experience or an equivalent result display directly on your wrist. Independent explanations from Tom’s Guide and TechRadar describe the same two-device workflow.
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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.*
Install both updates
Update the iPhone
- Open Settings.
- Tap General.
- Tap Software Update.
- Install iOS 18.6.1 if you are reproducing the original enabling path, or install the currently offered compatible release when following Apple’s present-day update flow.
Update the Apple Watch
- Open the Watch app on the paired iPhone.
- Tap General.
- Tap Software Update.
- Install watchOS 11.6.1, or the compatible version offered by the current update path.
Keep the watch near the iPhone and on its charger with sufficient battery while updating. Apple can change exact update prerequisites, so follow any additional prompts shown on your devices.
Where to find a reading
After both devices finish updating, open:
Health app → Browse → Respiratory → Blood Oxygen
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.*
The reading is on the iPhone, not in a restored on-watch display. If you are looking only for a Blood Oxygen app on the watch, you can conclude that the redesigned U.S. implementation is being mistaken for the original one.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.If Blood Oxygen does not appear
Work through the eligibility and setup checks before attempting more disruptive actions:
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![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.
- Only one device was updated: install the required software on both the iPhone and Apple Watch.
- Wrong app or location: check Health → Browse → Respiratory → Blood Oxygen on the paired iPhone.
- Wrong model: Apple identified only Series 9, Series 10, and Ultra 2 for this restoration.
- Wrong region: a non-U.S. watch follows its own feature history; the U.S. restoration does not apply automatically.
- The watch already had Blood Oxygen: the update does not create a new version of the original feature.
- Beta or later software branch: behavior can differ from the original 18.6.1/11.6.1 rollout, so check the software versions and Apple’s current support guidance.
- Refresh delay: after installation, allow the devices to complete syncing and recheck the Health app. Apple’s announcement does not guarantee instant activation on every unit.
Do not rely on unofficial downgrade procedures, erasing the watch, or community workarounds as guaranteed fixes. User reports can describe inconsistent activation, but they are not Apple’s stated requirements.
What the update does not change
- It does not add Blood Oxygen to every Apple Watch sold in the United States.
- It does not install a new sensor or turn an ineligible model into an eligible one.
- It does not remove the need for the paired iPhone to calculate and show results on affected U.S. units.
- It does not make the feature a medical diagnostic device.
Wellness, not diagnosis
Blood Oxygen readings can be influenced by fit, movement, skin contact, temperature, circulation, and other conditions. Treat them as wellness information, not a substitute for a clinical pulse oximeter, professional testing, or medical advice. If you have concerning symptoms, contact a health professional rather than interpreting an Apple Watch result yourself.
Should you replace your watch?
For an eligible U.S. Series 9, Series 10, or Ultra 2 that works normally, installing the updates is the sensible first step; buying another watch is not required just to regain access to Blood Oxygen data. Consider replacement when the actual problem is unsupported software, physical damage, failing battery, or service eligibility—not merely the former regional feature disablement.
If you are buying, verify the exact unit’s region and Blood Oxygen status instead of relying only on the model name. Apple’s current watch information is at apple.com/watch, and its shopping page is apple.com/shop/buy-watch. AppleCare+ may help with covered hardware damage or battery service, but it cannot convert a region-locked or otherwise ineligible watch into an eligible one; see AppleCare+ details.
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iOS 18.6.1 and watchOS 11.6.1 restored Blood Oxygen access on affected U.S.-sold Series 9, Series 10, and Ultra 2 watches beginning August 14, 2025. The practical workflow is different: the watch gathers the data, the paired iPhone calculates it, and the result appears in Health under Respiratory. Confirm the model, U.S. origin, and prior feature state, update both devices, and look on the iPhone rather than expecting the original on-wrist display.
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