Apple Watch Blood Oxygen has already returned to the United States. Apple restored it on August 14, 2025, with iOS 18.6.1 and watchOS 11.6.1 for some U.S. Apple Watch Series 9, Series 10, and Ultra 2 units that originally shipped without the feature.
There is an important catch: on the affected U.S. models, the watch collects the optical sensor data but the paired iPhone performs the final Blood Oxygen calculation. You start the measurement on the watch, but view the result in iPhone Health → Search → Respiratory → Blood Oxygen. It does not appear directly on the watch or in the Vitals app for affected U.S. units with part numbers ending in LW/A.
The short answer: Apple used an iPhone-based redesign, not a settlement
The original question—whether Blood Oxygen might return through a Masimo settlement, license, or hardware change—came from a September 30, 2024 9to5Mac opinion article. That article discussed possible outcomes after Masimo CEO Joe Kiani’s departure, including a speculative commercial arrangement involving Masimo hospital equipment and Apple Health.
That theory was not evidence of a disclosed Apple–Masimo agreement. Apple ultimately restored the feature by changing where the calculation takes place. The watch continues to gather the underlying optical signal, while the iPhone calculates and stores the result.
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The result is a feature that is available again, but does not reproduce every part of the original Apple Watch experience.
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- Original implementation: the watch calculated and displayed the Blood Oxygen result.
- Redesigned U.S. implementation: the watch gathers the sensor signal and sends it to the paired iPhone for processing.
- What you see: the result is stored in the iPhone Health app, not displayed on the affected watch.
- What remains unavailable: Blood Oxygen is not included in the Vitals app on affected U.S. LW/A watches.
Which Apple Watches have Blood Oxygen?
Model name alone is not enough to determine the exact experience. The country where the watch was sold, its purchase date, and its part number can all matter.
| Apple Watch category | Blood Oxygen status |
|---|---|
| Older Apple Watches that already included Blood Oxygen | The August 2025 update did not change these units. They retain the original experience available to their model and region, subject to Apple’s current software and availability requirements. |
| Some U.S. Series 9, Series 10, and Ultra 2 units that shipped without Blood Oxygen | Apple restored the redesigned feature through the iPhone-processing implementation after the required updates. |
| Current Apple Watch Series 11 and Ultra 3 | Apple’s current comparison information lists the Blood Oxygen app and says measurements are calculated and viewed on the iPhone in Health. |
| Apple Watch SE | Blood Oxygen is not supported on SE models. |
Apple’s general support documentation says the feature is supported on Apple Watch Series 6 or later and all Apple Watch Ultra models, but not Apple Watch SE. However, that broad model range should not be treated as proof that every Series 6 through Series 8 configuration received the same U.S. software restoration. Apple’s August 2025 announcement specifically referred to some Series 9, Series 10, and Ultra 2 users.
For a current model comparison, check Apple’s Apple Watch comparison page and the Apple Watch models guide. Availability also varies by country and region.
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Apple identifies affected U.S. units sold on or after January 18, 2024 by part numbers ending in LW/A. These are the watches for which Apple describes the iPhone-based Blood Oxygen behavior: analysis is performed on the iPhone, results cannot be viewed on the watch, and Blood Oxygen is excluded from Vitals.
To check the part number:
- Open the Watch app on the paired iPhone.
- Tap My Watch → General → About.
- Tap the Model Number field to switch between the part number and the A-number model identifier.
- Check whether the part number ends in LW/A.
Apple documents this process in its model and serial-number identification guide. A part-number check is more useful than relying only on the retail model name.
How the redesigned Blood Oxygen feature works
Apple did not simply turn off and then turn back on an unchanged feature. The public technical description in U.S. Customs and Border Protection ruling H338254 describes Apple’s “Redesign 2 Watch” as retaining the optical sensing hardware while moving the processors responsible for the final Blood Oxygen calculation from the watch to the iPhone.
In practical terms, the process works like this:
- The Apple Watch shines light into the wrist and detects the reflected light using its optical sensor.
- The watch records the underlying photoplethysmography, or PPG, signals.
- The watch sends the relevant signal data to the paired iPhone.
- The iPhone performs the calculation that produces the Blood Oxygen result.
- The result is stored and displayed in the iPhone Health app.
Some of the technical description in the CBP ruling is redacted. The public documents establish where the processing occurs, but they do not provide a complete public specification of every algorithmic detail.
It is therefore too strong to claim that Apple changed the sensor hardware, changed the medical algorithm, or proved that the redesigned implementation is identical in accuracy, timing, or data handling to the original on-watch version. Apple’s solution changed the division of work between the watch and iPhone; the available public evidence does not establish every other technical comparison.
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How to use Blood Oxygen on an affected U.S. Apple Watch
At the time Apple restored the feature, the required versions were iOS 18.6.1 on the iPhone and watchOS 11.6.1 on the watch. If you are using a later generation of iOS or watchOS, Apple’s current compatibility requirements take priority. Its current compatibility table should be checked before troubleshooting a pairing or update problem.
Enable and take a reading
- Update the paired iPhone and Apple Watch to compatible software.
- On the watch, open Settings → Blood Oxygen.
- Turn on Blood Oxygen Measurements.
- Open the Blood Oxygen app on the watch.
- Rest your arm on a table or in your lap, keep the wrist flat, and tap Start.
- Hold still for the approximately 15-second countdown.
- On affected U.S. LW/A watches, open the iPhone’s Health app and select Search → Respiratory → Blood Oxygen.
The watch can also take periodic background measurements during the day and overnight when the feature is enabled. Apple’s Blood Oxygen instructions cover the setup and viewing paths.
Important prerequisites
- Compatible hardware: Apple Watch Series 6 or later and Apple Watch Ultra models support Blood Oxygen; Apple Watch SE does not.
- Compatible iPhone: the iPhone must support the relevant Apple Watch software and be paired with the watch.
- Software: the restoration launched with iOS 18.6.1 and watchOS 11.6.1. Apple’s requirements can change; for example, Apple’s current watchOS 26 pairing baseline requires an iPhone 11 or later running iOS 26, according to its compatibility table.
- Age: Apple says Blood Oxygen is not available to users under 18.
- Region: availability varies by country and region.
Why Apple removed Blood Oxygen from U.S. watches
Apple introduced Blood Oxygen with the Apple Watch Series 6 in September 2020. Masimo later accused Apple of infringing patents involving light-based pulse oximetry and filed an International Trade Commission complaint in June 2021.
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The ITC ultimately found violations involving U.S. Patent Nos. 10,912,502 and 10,945,648. On October 26, 2023, it issued a limited exclusion order covering Apple Watch imports that used the infringing implementation. The order concerned importation and sale of covered products; it was not a general ruling that every Apple Watch with an optical sensor was unlawful.
Apple paused U.S. sales of affected watches in December 2023. Beginning in January 2024, it sold certain U.S. Apple Watch units without the Blood Oxygen function. Apple’s support materials use January 18, 2024, as the cutoff date associated with the affected U.S. part numbers ending in LW/A.
The original ITC exclusion order and related documents are available through the USITC. The resulting retail change explains why a watch could contain the relevant optical hardware yet be sold in the U.S. without an active Blood Oxygen feature.
What routes could have brought the feature back?
Before Apple’s 2025 restoration, several outcomes were plausible in principle:
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- License or settlement: Apple could have paid Masimo for rights to use the disputed technology.
- Hardware redesign: Apple could have changed the optical sensing system in future watches.
- Software or signal-processing redesign: Apple could have changed how the signal was processed or divided the processing between devices.
- Legal victory: Apple could have overturned the ITC decision or shown that a redesigned product fell outside the exclusion order.
- Commercial cooperation: The 2024 9to5Mac article speculated about a deal involving Masimo’s hospital equipment and Apple Health rather than a conventional patent license.
The last possibility was commentary, not a disclosed agreement. Apple did not need a public settlement announcement to restore the redesigned feature. It used the processing redesign and pursued the legal question of whether that product fell within the existing order.
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Why the redesign survived the relevant U.S. trade proceeding
On January 7, 2025, CBP published its ruling describing Apple’s second redesign. The key change was that the Apple Watch continued to collect the sensor signal, while the iPhone handled the final calculation.
On April 17, 2026, the ITC declined to review the judge’s finding that Apple’s redesigned products did not infringe the asserted Masimo patents and terminated the related modification and enforcement proceeding. In practical terms, the redesigned U.S. Blood Oxygen implementation was not treated as the infringing implementation covered by the original exclusion order.
That result does not mean Apple won every part of the broader patent dispute. It means the redesigned product survived this particular ITC import-enforcement question.
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No—not in the broad sense. Several legal tracks need to be kept separate:
1. The original ITC exclusion order
The Federal Circuit affirmed the original ITC determination on March 19, 2026. The ITC’s exclusion-order database lists the relevant order as expiring on August 25, 2028. That order remains relevant to the older infringing implementation, but it should not be described as a continuing ban on the redesigned feature.
See the Federal Circuit opinion and the USITC exclusion-order database.
2. The redesigned-product proceeding
The April 2026 ITC result addressed whether Apple’s redesigned products were subject to the existing order. The ITC concluded that the redesigned products did not infringe the asserted patents in that proceeding. This is why the feature can be available to U.S. users even though Apple lost important parts of the original patent fight.
3. A separate federal damages case
A separate federal case later preserved a roughly $634 million Masimo patent award against Apple in a post-trial ruling reported on July 20–21, 2026. That case concerns monetary patent liability under a separate litigation track. It is not the same as the ITC import dispute and does not establish that the redesigned Blood Oxygen feature was banned.
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Similarly, Masimo’s later transition to a wholly owned Danaher subsidiary on June 10, 2026, does not turn the 2024 settlement speculation into evidence that a license or cooperation agreement caused the feature’s return. Danaher’s acquisition is documented in its company announcement.
What the redesigned feature does not restore
You cannot check the result directly on the affected watch
The measurement is initiated on the Apple Watch, but the result must be viewed on the paired iPhone. This matters most to people who bought a cellular Apple Watch expecting to leave the iPhone behind while still accessing health information.
It is not part of Vitals on affected LW/A watches
If you look in the watchOS Vitals app and do not see Blood Oxygen, that can be normal for an affected U.S. unit. Apple specifically excludes Blood Oxygen from Vitals for these watches. The Vitals user guide describes the limitation.
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The public legal and technical materials describe the location of the processing, not an independent accuracy comparison between the original and redesigned implementations. Treat claims that the two experiences are exactly equivalent as unverified unless Apple or an appropriate independent authority provides supporting evidence.
It remains a wellness feature
Apple says Blood Oxygen is intended for general wellness and is not intended for medical use, self-diagnosis, or consultation with a doctor. Do not use a single watch reading to diagnose low blood oxygen or make a medical decision. Anyone who needs medically oriented oxygen monitoring should follow a clinician’s recommendation and use equipment intended and authorized for that purpose.
Blood Oxygen troubleshooting
If the feature does not appear or a reading fails, work through these checks in order:
- Confirm the model. Make sure the watch is not an Apple Watch SE.
- Check the part number. Use iPhone Watch app → My Watch → General → About, then tap Model Number. For affected U.S. units, check for the LW/A suffix.
- Complete both updates. The watch and paired iPhone must finish installing compatible versions; restarting an update halfway through will not restore the app.
- Look in the correct place. On affected U.S. units, check Health → Search → Respiratory → Blood Oxygen on the iPhone. Do not expect the result on the watch display.
- Do not use Vitals as the only test. Blood Oxygen is not shown in Vitals on affected LW/A watches.
- Check restrictions. Confirm the user is 18 or older and that the feature is available in the watch’s country or region.
- Improve the fit. If the app exists but readings repeatedly fail, position the watch above the wrist bone, keep the sensor against the skin, use a snug but comfortable fit, and remain still for the full 15 seconds.
Loose or overly tight bands, poor skin contact, placement over the wrist bone, movement, low skin perfusion, and other physiological or environmental factors can interfere with a reading. Apple’s Apple Watch wearing guidance explains the recommended fit.
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For a prospective U.S. buyer, the first question is not simply whether the watch has a Blood Oxygen sensor. Ask where the result will be calculated and displayed.
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- Choose the redesigned experience if you are comfortable using the paired iPhone to calculate and view results, and you want a current Apple Watch that supports the feature.
- Be cautious with used or imported watches if the seller describes Blood Oxygen only by model name. Verify the region, purchase history, part number, software eligibility, and whether the result appears on the watch or only in iPhone Health.
- Do not buy an Apple Watch expecting clinical monitoring. Apple describes the feature as a general-wellness tool, not a replacement for authorized medical equipment.
- Do not assume every Series 9, Series 10, or Ultra 2 is identical. Apple restored the feature to some affected U.S. units, while other regional and older configurations may have a different implementation.
The practical buying distinction is therefore straightforward: the newer U.S. implementation brings Blood Oxygen back, but it is an iPhone-dependent feature, not the original on-watch experience.
Timeline of the Blood Oxygen dispute
- September 2020: Apple introduced Blood Oxygen with Apple Watch Series 6.
- June 2021: Masimo filed its ITC complaint concerning light-based physiological measurement devices.
- October 26, 2023: The ITC issued its original violation determination and remedial orders.
- December 2023–January 2024: Apple paused U.S. sales of affected watches and began selling certain units without Blood Oxygen.
- January 18, 2024: Apple’s documented cutoff date for affected U.S. units identified by part numbers ending in LW/A.
- September 30, 2024: 9to5Mac published speculation that Masimo leadership changes might create an opening for a settlement or commercial arrangement.
- January 7, 2025: CBP issued ruling H338254 describing Apple’s second redesign and the movement of final processing to the iPhone.
- August 14, 2025: Apple restored the redesigned Blood Oxygen feature in the U.S. through iOS 18.6.1 and watchOS 11.6.1.
- March 19, 2026: The Federal Circuit affirmed the original ITC determination against the original implementation.
- April 17, 2026: The ITC terminated the redesigned-product proceeding after declining review and concluding that the redesigned products did not infringe the asserted patents.
- July 20–21, 2026: A separate federal case preserved a roughly $634 million Masimo patent award against Apple.
Frequently Asked Questions
Can I see Blood Oxygen results on my Apple Watch?
On affected U.S. Apple Watch units with part numbers ending in LW/A, no. You start the measurement on the watch, but the paired iPhone calculates and displays the result in Health → Search → Respiratory → Blood Oxygen. Older units that originally included the feature may retain the original on-watch experience, depending on model, region, and software.
Does the redesigned feature work without an iPhone nearby?
The redesigned U.S. feature relies on the paired iPhone for the final calculation and viewing. The watch can collect the optical signal, but it is not a standalone way to view the completed Blood Oxygen result on the watch.
Does my U.S. Apple Watch Series 9, Series 10, or Ultra 2 have Blood Oxygen?
Some U.S. units that shipped without the feature received Apple’s redesigned version through iOS 18.6.1 and watchOS 11.6.1. Check the watch’s exact model, region, software, and part number rather than assuming every unit of the same model is covered.
Why is Blood Oxygen missing from the Vitals app?
That is expected on affected U.S. LW/A watches. Apple says Blood Oxygen is not included in Vitals for those units, even though measurements can be initiated on the watch and viewed in the iPhone Health app.
Is Apple Watch Blood Oxygen medical-grade?
Apple describes it as a general-wellness feature and says it is not intended for medical use, self-diagnosis, or consultation with a doctor. Do not use an individual reading to diagnose a condition or replace clinician-recommended monitoring.
Does the Masimo case mean Apple might disable Blood Oxygen again?
The original ITC order and separate federal patent litigation remain distinct from the redesigned-product decision. The ITC concluded that the redesigned products did not infringe the asserted patents in the relevant proceeding, so the feature is currently available under that redesign. Future availability can still depend on Apple’s software, regional support, and further legal developments; there is no basis to describe the feature as permanently guaranteed.
The Bottom Line
Bottom line: Apple Watch Blood Oxygen is back in the U.S., but through a redesigned architecture. The watch still collects the optical data; the paired iPhone calculates and displays the result. Apple did not need the speculative 2024 settlement route to restore it, and the ITC cleared the redesigned implementation even while the original exclusion order and separate Masimo patent litigation remain active legal issues.
