Apple restored Blood Oxygen to affected U.S. Apple Watch Series 9, Series 10, and Ultra 2 units on August 14, 2025, through iOS 18.6.1 and watchOS 11.6.1. It is a redesigned experience: the Watch collects sensor data, but the paired iPhone calculates the result and displays it in the Health app. As of August 2026, Series 11 and Ultra 3 are Apple’s current flagship watches and list Blood Oxygen; the SE 3 does not.
What returned—and what changed
Apple’s August 2025 update restored Blood Oxygen functionality to certain U.S. watches that had shipped without the original feature. It did not simply reinstate the same on-watch workflow for those affected units. The Watch gathers the sensor information, while the paired iPhone performs the calculation. Apple says results appear in the Health app, in the Respiratory area. Apple’s announcement and support documentation describe the redesigned arrangement.
That distinction matters if you expect the Watch to calculate and show a reading by itself. On affected U.S. units using the restored experience, the iPhone is part of the measurement workflow.
Which Apple Watches have Blood Oxygen?
| Watch | What to know |
|---|---|
| Series 9, Series 10, Ultra 2 | Apple’s 2025 restoration covered affected U.S. units that lacked the original Blood Oxygen feature. The update does not apply universally to every watch with one of these model names. |
| Series 11, Ultra 3 | As of August 18, 2026, Apple lists Blood Oxygen on both current flagship models. Consult the model-specific documentation for the implementation on a particular regional unit. |
| SE 3 | Apple’s current materials do not list Blood Oxygen among its features. |
| Older watches or watches bought outside the U.S. | The U.S.-specific restoration did not announce a universal activation for all older watches. Some watches may already have the original feature; Apple said the 2025 change did not affect units purchased outside the U.S. |
Apple’s model and region guidance notes that affected U.S. configurations can generally be identified by part numbers ending in LW/A. For the current lineup, Apple lists Series 11 and Ultra 3 with Blood Oxygen; its compatibility information identifies Series 11, Ultra 3, and SE 3 as the current generation.
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How to update an eligible watch
The minimum software versions in Apple’s original restoration path were iOS 18.6.1 on the paired iPhone and watchOS 11.6.1 on the Watch. Those are minimum restoration versions, not necessarily the current software requirements for a newer Watch. Current models may require newer operating systems; Apple’s compatibility page lists iOS 26 or later and watchOS 26 or later for Series 11, SE 3, and Ultra 3.
- Update the iPhone: On the iPhone paired with the Watch, open Settings → General → Software Update and install a compatible iOS version. For the original restoration, the minimum was iOS 18.6.1.
- Update the Watch: In the iPhone’s Watch app, go to My Watch → General → Software Update. Alternatively, on the Watch, open Settings → General → Software Update. For the original restoration, the minimum was watchOS 11.6.1.
- Meet update prerequisites: Apple says the Watch should have at least 50% charge and the iPhone should be connected to Wi-Fi during the update. Keep the devices paired and allow the Watch to finish installing and restart.
- Check Health: Open Health on the iPhone and look for Blood Oxygen data in the Respiratory area. Depending on the model and software, use the Blood Oxygen app or the relevant Health entry to start or review readings.
Apple’s full update instructions are at Update your Apple Watch.
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If Blood Oxygen does not appear
First confirm that the watch is an eligible Series 9, Series 10, or Ultra 2 U.S. unit that lacked the original feature, that both devices have completed compatible updates, and that the Watch is paired with the iPhone whose Health app you are checking. If the Watch already had the original feature, the redesigned restoration may not be relevant to it. Also check that Health is using the Apple Account and paired Watch you expect.
If the feature is still missing after checking those details, restart both devices and check again. If it remains unavailable, contact Apple Support. A lack of historical readings does not necessarily indicate a fault: the feature may only have been enabled after the update, measurements may not yet have been collected, or the Watch may not have been worn with suitable fit and contact. Do not assume the restored feature will backfill readings from the period it was disabled.
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Why Apple disabled it in the U.S.
Apple disabled Blood Oxygen on certain U.S. Apple Watches amid a patent dispute with medical-technology company Masimo. Affected U.S. sales configurations were associated with part numbers ending in LW/A. Apple said the 2025 restoration followed a recent U.S. Customs ruling. That product change does not, by itself, establish that the broader Apple–Masimo legal conflict is permanently over; the feature’s availability and the final status of litigation are separate questions. The Federal Circuit’s opinion in the case is available here.
What to know before relying on a reading
Apple describes Blood Oxygen as a general-wellness feature, not a medical device or diagnostic tool. A smartwatch reading cannot prove that oxygenation is adequate, establish respiratory health, or rule out illness. Fit, movement, skin contact, tattoos, circulation, temperature, and other measurement conditions can affect results. Apple’s use guidance is at About Blood Oxygen measurements.
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If a reading concerns you, do not use repeated Watch checks to diagnose yourself. Pay attention to symptoms and speak with a qualified medical professional; seek urgent care for severe or rapidly worsening symptoms.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Should an affected owner buy a new Watch?
Usually not solely to regain Blood Oxygen. If you own an eligible affected Series 9, Series 10, or Ultra 2, the software update is the route Apple provided. The restored U.S. experience does require the paired iPhone for calculation and result display, so it may not suit someone who wants a standalone Watch-only workflow.
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Consider replacing a Watch for broader reasons—such as battery condition, warranty, performance, or other features—not simply because Blood Oxygen was once unavailable. For a used or refurbished Series 9, Series 10, or Ultra 2, verify the individual unit rather than relying on its model name: region, part number, sale date, replacement history, and whether it had the original feature can affect what experience it offers. Ask for part-number information and confirm the Watch is not Activation Locked.
Current lineup status in 2026
The restoration was announced in 2025; it is not a newly launched feature in 2026. Apple’s current flagship models are Series 11 and Ultra 3, both of which list Blood Oxygen. SE 3 does not list it. The earlier Series 9, Series 10, and Ultra 2 remain relevant to owners and used-watch buyers, but their U.S. feature behavior depends on the particular unit and configuration.
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