The short version: newer Apple Watches sold in the United States lost the blood oxygen (SpO2) feature because of a patent dispute, not a hardware failure. Medical-device company Masimo argued that Apple’s pulse oximetry technology infringed its patents, and the U.S. International Trade Commission (ITC) agreed. That ruling led to an import ban on the affected models, so starting in early 2024 Apple sold the Series 9 and Ultra 2 in the US with the blood oxygen feature switched off. The sensor was still physically present on the watch; Apple simply disabled the software that reported a reading. In 2025 Apple introduced a workaround that moves the calculation to the paired iPhone, restoring a form of the feature for US owners.
- The cause was a legal patent fight with Masimo, resolved against Apple at the ITC
- The sensor hardware stayed in the watch; only the software feature was turned off
- Watches bought before the ban, and models sold outside the US, kept the feature
- A 2025 software update restored blood oxygen by calculating the result on the paired iPhone
What actually happened
Blood oxygen measurement uses pulse oximetry: the watch shines light into your wrist and estimates the percentage of oxygen your red blood cells are carrying. Apple added this feature with the Apple Watch Series 6 in 2020 and carried it forward through later models.
Masimo, a company that builds professional pulse oximeters used in hospitals, accused Apple of infringing patents tied to that technology. Masimo pursued the case at the U.S. International Trade Commission, a federal agency that can block the import of products found to infringe US patents. In late 2023 the ITC issued an exclusion order against the Apple Watch models that included the disputed feature.
Because Apple Watches are manufactured overseas, an import ban effectively stops Apple from bringing them into the country to sell. Rather than pull the watches entirely, Apple chose to remove the blood oxygen feature from units sold in the US, which allowed it to keep selling the Series 9 and Ultra 2 without violating the order.
Which watches were affected
The change hit specific models sold through specific channels in the US. The timing of your purchase and the country you bought in both matter.
| Situation | Blood oxygen status |
|---|---|
| Series 9 / Ultra 2 bought in the US after the ban (early 2024) | Feature disabled at purchase |
| Series 6 through Series 9 / Ultra bought in the US before the ban | Feature still works (not removed retroactively) |
| Any affected model bought outside the US | Feature works normally |
| Older models without the sensor (Series 5 and earlier, SE line) | Never had blood oxygen |
| US models after the 2025 iPhone-based update | Feature restored via paired iPhone calculation |
The 2025 workaround explained
In 2025 Apple rolled out a redesigned version of the feature through software updates to iOS and watchOS. Instead of the watch measuring, computing, and displaying the reading entirely on its own, the sensor data is sent to the paired iPhone, where the oxygen result is calculated and shown in the Health app. This design was structured to sit outside the scope of the import order.
For everyday users the practical result is similar—you can still get an on-demand SpO2 reading—but the experience differs slightly because the number surfaces through the iPhone rather than fully on the watch face.
Does this affect how accurate the reading is?
The legal story is separate from the accuracy story. Even before any of this, consumer wrist-based SpO2 was always a wellness feature rather than a medical-grade diagnostic tool. Wrist optical sensors can be thrown off by motion, cold hands, skin tone, tattoos, poor fit, and positioning, which is why readings are best treated as trend information rather than a clinical result. We cover the underlying technology and its limits in more depth in our guide to what SpO2 on a smartwatch is and how accurate it is.
This is a common theme across wrist sensors. The same caveats apply to features like smartwatch blood pressure and to what an Apple Watch ECG actually measures—useful signals, but not replacements for validated medical equipment.
What it means if you’re buying today
If blood oxygen matters to you, check the exact status of the model and region before you buy, since the situation has evolved through software updates and legal developments. A few practical pointers:
- Confirm whether the specific US unit you’re considering includes the restored, iPhone-based feature.
- Remember that other health features on these watches—heart rate, irregular rhythm notifications that may flag AFib, ECG, and sleep tracking—were never part of the dispute and continued to work.
- If you’re new to the platform, our walkthrough on how to set up an Apple Watch for the first time covers activating health features during setup.
Blood oxygen is rarely the deciding factor for most buyers. Battery life, comfort, and everyday reliability tend to matter more day to day—worth weighing alongside our look at which smartwatches last the longest.
Frequently asked questions
Did Apple remove the blood oxygen sensor from the watch?
No. The pulse oximetry sensor stayed physically in the affected US watches. Apple disabled the software feature so the watch would not report a reading, which is what allowed sales to continue under the import order.
Does my existing Apple Watch still have blood oxygen?
If you bought an affected model in the US before the ban took effect, the feature was not removed from your watch. Models sold outside the US also kept the feature. Only newly sold US units were shipped with it disabled.
Is the restored feature the same as before?
Functionally similar, but the design changed. After the 2025 update, the oxygen result is calculated on the paired iPhone rather than entirely on the watch, and the reading surfaces through the Health app. For casual use the difference is mostly behind the scenes.
Should I trust a smartwatch blood oxygen number medically?
Treat it as a wellness estimate and a trend indicator, not a diagnosis. Wrist readings can be affected by movement, fit, temperature, and other factors. For anything health-related, talk to a qualified healthcare professional.
Medical disclaimer
This article is general information and is not medical advice. Smartwatch blood oxygen features are intended for general wellness and fitness, not to diagnose, treat, cure, or prevent any condition. Readings may indicate a trend but should not replace professional evaluation. Always consult a qualified healthcare professional about your health, symptoms, or any device readings that concern you.