Apple is returning a key health tool to some of its newer smartwatches in the United States. The blood oxygen monitoring feature is being reactivated for the Apple Watch Series 9, Series 10, and Ultra 2 models. This good news comes after the feature was removed from new devices sold in the U.S. starting in early 2024 because of a legal disagreement.
The change comes through a software update released on August 14, 2025. If you have one of these newer watches and live in the U.S., you’ll need to update your iPhone to iOS 18.6.1 and your Apple Watch to watchOS 11.6.1 to get the feature back. This update was made possible by a new ruling from U.S. Customs. It’s important to know this doesn’t affect users who already had the feature or those outside the United States.
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What Happened to Blood Oxygen Monitoring?
Apple had to remove blood oxygen monitoring from its latest watches in January 2024. This happened because of a patent fight with Masimo, a medical technology company. The International Trade Commission ruled that Apple’s blood oxygen sensors broke Masimo’s patent rights. To keep selling watches in the US, Apple removed the feature from new devices.
Before this ruling, people could check their blood oxygen levels right on their watch. They got instant readings and could track their health data easily.
How the New System Works
The updated blood oxygen feature works differently now. Here’s what changed:
- Your Apple Watch still uses its sensors to collect blood oxygen data
- Your iPhone does all the calculations instead of the watch
- Results show up in the Respiratory section of the Health app on your iPhone
- You can’t see readings directly on your watch anymore
Previously, users could see their blood oxygen levels directly on the watch face. The new method requires you to check your phone for the results, which is less immediate but restores access to this valuable health data. This system needs both devices working together. You must update your iPhone to iOS 18.6.1 and your Apple Watch to watchOS 11.6.1.
Who Can Use This Feature?
The updated blood oxygen monitoring only works for:
- Apple Watch Series 9 owners
- Apple Watch Series 10 owners
- Apple Watch Ultra 2 owners
- People who bought these watches in the US after January 18, 2024
Your watch won’t get this feature if you:
- Already have blood oxygen monitoring working
- Bought your watch outside the United States
- Own an older Apple Watch model
How to Enable Blood Oxygen Monitoring
To enable the blood oxygen feature, you must update the software on both your iPhone and your Apple Watch. Follow these simple steps to ensure you get the feature correctly.
Step 1: Updating Your iPhone
- Before you start, it’s always a good idea to back up your iPhone.
- Open the “Settings” app.
- Go to “General” and then select “Software Update.”
- Tap “Update Now” to download and install iOS 18.6.1. Your phone will need to restart to complete the installation.
Step 2: Updating Your Apple Watch
- After your iPhone is updated, open the “Watch” app on your iPhone.
- Go to the “General” tab and tap on “Software Update.”
- Choose to download and install watchOS 11.6.1.
Both devices must be updated for the blood oxygen monitoring to work. After updating, the redesigned feature may take up to 24 hours to activate, but some users report that opening the Health app on your iPhone or ECG app on the watch can speed up the process.
What This Means for Your Health Tracking
Blood oxygen monitoring helps you understand your respiratory health. Normal blood oxygen levels range from 95% to 100%. The Apple Watch can detect low oxygen levels, which might indicate health problems.
Studies show that Apple Watch blood oxygen measurements can be accurate when compared to medical equipment. The technology works by shining light through your skin to measure how much oxygen is in your blood.
The Legal Battle Continues
Apple found this workaround through a recent U.S. Customs ruling. However, the company is still fighting the patent case with Masimo. This new system shifts data processing to the iPhone, which likely helps Apple avoid the patent issues.
The patent dispute cost Apple significantly. Sales reportedly dropped 10% after removing the feature, losing about $16.58 billion according to S&P Global Market Intelligence.
What About International Users?
People outside the United States never lost blood oxygen monitoring. The patent ruling only affected US sales. International Apple Watch owners continue using the original system that shows results directly on their watch.
This update gives US users access to blood oxygen data again, even though it works differently than before. While you can’t see instant readings on your wrist anymore, you can still track your respiratory health through the iPhone Health app.