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Yes, Blood Oxygen is back on qualifying Apple Watch models in the United States. Apple restored the feature on August 14, 2025, with iOS 18.6.1 and watchOS 11.6.1. But affected U.S. watches do not work exactly as they did before: the watch captures the sensor data, while the paired iPhone performs the analysis and displays the result in the Health app—not on the watch itself.
What “back” means
Apple introduced Blood Oxygen with the Apple Watch Series 6. The feature was later disabled on certain U.S. models amid a patent dispute with medical-device company Masimo involving pulse-oximetry technology.
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Apple’s redesigned implementation became available for qualifying U.S. Apple Watch Series 9, Series 10, and Apple Watch Ultra 2 units that originally shipped without Blood Oxygen. Apple says the watch still collects the optical sensor data, but the paired iPhone processes it and saves the result in Health. See Apple’s announcement about the U.S. feature.
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International models purchased outside the United States were not affected by this U.S. dispute and retained the original experience, subject to Apple’s usual country, model, and purchase-date restrictions.
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Which Apple Watch models support Blood Oxygen?
| Model or category | Status | Where results appear |
|---|---|---|
| Qualifying U.S. Series 9, Series 10, and Ultra 2 units that shipped without the feature | Redesigned Blood Oxygen feature available after eligible updates | Paired iPhone’s Health app |
| Apple Watch Series 11 | Apple lists Blood Oxygen support in the current U.S. lineup | Verify the exact model and part number |
| Apple Watch Ultra 3 | Apple lists Blood Oxygen support in the current U.S. lineup | Verify the exact model and part number |
| Apple Watch SE 3 | Blood Oxygen is not supported | Not applicable |
| Older Series 6 or later and Ultra models | Region- and model-dependent | Depends on the original or redesigned implementation |
U.S. models with part numbers ending in LW/A |
iPhone-based analysis | Health on the paired iPhone |
Apple’s general support documentation describes Blood Oxygen as available on Apple Watch Series 6 or later and all Apple Watch Ultra models, but that broad statement does not mean every older U.S. watch received the redesigned feature. Eligibility depends on the hardware, sales region, software, and whether the original function was disabled.
How to identify an affected U.S. watch
For U.S. Apple Watch units purchased from Apple on or after January 18, 2024, a part number ending in LW/A indicates the iPhone-based implementation. On these watches, results are available exclusively in the iPhone Health app.
To check:
- Open the Watch app on the paired iPhone.
- Tap General, then About.
- Look for the model and part-number information.
Menu labels can vary slightly by watchOS version. Apple also provides device-identification guidance. Do not apply the LW/A rule automatically to a watch purchased outside the United States, and do not rely only on a retailer’s generic Series name.
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The original restoration required iOS 18.6.1 and watchOS 11.6.1. Apple’s current guidance is to update both devices to the latest compatible operating systems.
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- Charge the Apple Watch and iPhone.
- Update the paired iPhone to the latest compatible iOS version.
- Update the Apple Watch to the latest compatible watchOS version.
- Keep the devices paired and connected during setup.
- If necessary, download the Blood Oxygen app again from the App Store on the watch.
Installing an update does not restore Blood Oxygen on every U.S. Apple Watch. The exact model, region, and feature history still matter.
How to turn on Blood Oxygen
- On the Apple Watch, open Settings.
- Tap Blood Oxygen.
- Turn on Blood Oxygen Measurements.
If the setting or app is absent, confirm that the watch supports the feature in its sales region. Apple says the app is not available to users under 18.
How to take a reading
- Open the Blood Oxygen app on the Apple Watch.
- Wear the watch snugly but comfortably.
- Rest your arm on a table or in your lap.
- Keep your wrist flat with the display facing upward.
- Tap Start.
- Remain still during the 15-second countdown.
- Wait for the reading to be saved.
On a U.S. LW/A watch, it is normal for no result to appear on the watch after the measurement. The iPhone processes the data and displays the result in Health.
Where to find Blood Oxygen results
- Open Health on the iPhone.
- Tap Search.
- Tap Respiratory.
- Tap Blood Oxygen.
Health can show daily, weekly, monthly, and six-month views. Depending on the recorded data, it can also filter readings such as sleep or high-elevation measurements. Apple’s current setup and measurement instructions are in its Blood Oxygen guide.
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The important limitations
It is not the same as the old experience
On affected U.S. models, the measurement starts on the wrist but finishes on the iPhone. You cannot view the result directly on the watch, and Blood Oxygen is not included in the Vitals app on U.S. models with LW/A part numbers.
That absence from Vitals is expected. It does not mean the sensor or reading failed. Apple documents the restriction in its watchOS health-features guide.
It is a wellness estimate, not a diagnosis
Blood Oxygen estimates the percentage of oxygen carried by red blood cells. Apple says the feature is intended for general fitness and wellness, not medical use, diagnosis, or consultation with a doctor. Many people have readings around 95–100%, but some healthy people normally run lower, and readings can also be lower during sleep or at altitude.
Fit, movement, wrist position, cold skin, tattoos, and poor skin contact can affect a reading. A single unusual number should not be treated as a diagnosis. Persistent symptoms or health concerns require appropriate medical advice and, where necessary, a clinically appropriate device or evaluation.
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Blood Oxygen is also separate from ECG. ECG records an electrical heart rhythm; Blood Oxygen estimates oxygen saturation. Vitals is a broader overnight context feature that may include Blood Oxygen on supported models, but not on affected U.S. LW/A watches.
What to check when no result appears
- Software: Confirm that both the iPhone and Apple Watch are updated.
- Pairing: Make sure the iPhone is paired with the watch used for the measurement.
- Connection: Check Bluetooth and the watch’s connection to the iPhone.
- Setting: Confirm that Blood Oxygen Measurements is enabled.
- Technique: Tighten the fit slightly, keep the wrist flat, and remain still for the full countdown.
- Eligibility: Check the exact model, part number, region, and user age.
- Health setup: Confirm that the Health profile and relevant permissions are configured.
If the result appears in Health but not on the watch, first check whether the watch ends in LW/A. For those U.S. models, iPhone-only results are expected.
Should you buy an Apple Watch for Blood Oxygen?
For an existing qualifying owner, updating is the sensible first step. You do not need to buy a new watch to regain the redesigned feature, although you do need the paired iPhone for processing and viewing.
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For a new buyer, Blood Oxygen should be one consideration rather than the sole reason to choose a model. Apple’s U.S. shopping pages list the current models from:
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- Apple Watch Series 11: from $399; the mainstream option.
- Apple Watch Ultra 3: from $799; better suited to rugged use, outdoor sports, longer battery life, and premium construction.
- Apple Watch SE 3: from $249; lower-cost, but not compatible with the Blood Oxygen app.
Prices and availability can change. Check Apple’s current U.S. buying page before purchasing. If buying used, refurbished, imported, or from a third party, verify the exact model number, country of purchase, purchase date, and feature availability. A generic listing title is not enough, and an imported watch can have different regional, cellular, warranty, and support characteristics.
The Ultra should not be purchased solely for Blood Oxygen. Its higher price is more defensible for battery life, durability, GPS, and outdoor capabilities. If Blood Oxygen is the specific goal, investigate the supported Series line first. Apple Watch also remains a poor substitute for a clinically appropriate pulse oximeter or medical evaluation.
Why the legal story is not quite finished
Apple’s return of Blood Oxygen reflects a redesigned implementation and a U.S. Customs ruling that allowed that approach; it does not prove that every part of the Apple–Masimo dispute has permanently ended.
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Random freezes, missing sound and display glitches usually trace back to one bad driver. Find and replace yours safely.Free scan · under a minuteApple introduced the feature in 2020, disabled it on affected U.S. units after the dispute escalated, and announced the redesigned U.S. experience on August 14, 2025. In 2026, the dispute continued to produce court and trade-tribunal activity. A Federal Circuit opinion filed March 19, 2026, addressed an Apple–Masimo patent matter, and subsequent reporting described Apple prevailing in a further challenge to the redesigned implementation. Those developments should not be simplified into a claim that all litigation is permanently over.
For owners, the practical conclusion is simpler: Blood Oxygen is available again on eligible U.S. watches, but affected models retain the iPhone-processing architecture and its Health-only results.
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