To measure blood oxygen on your Apple Watch, open the Blood Oxygen app and tap start.
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Why is blood oxygen monitoring important?
Jimmy Westenberg / Android Authority
Blood oxygen measurements, or SpO2 levels, represent what percentage of oxygen you have in your blood. Since we depend on oxygen to function, this measurement can be an important indicator of our overall health. Higher SpO2 levels are a good thing. A normal reading is anything between 95% and 99%. Low levels of blood oxygen, meanwhile, can lead to dangerous symptoms known as hypoxemia.
How to set up background readings
Blood oxygen monitoring is available on the Apple Watch Series 6, Series 7, Series 8, and Ultra. Make sure your device is running the latest watchOS to take advantage of this useful feature. According to Apple, this tool is designed for users aged 18 and older. When you set up your device for the first time, the Blood Oxygen app should be installed in the Health app. If needed, you can reinstall the app from the App Store on your Apple Watch.
- On your paired iPhone, open the Health app and follow the onscreen prompts to set up the Blood Oxygen app. If you don’t receive a prompt, tap the Browse tab.
- Tap Respiratory.
- Tap Blood Oxygen, then scroll down to and tap Enable.
Your Apple Watch will occasionally measure your blood oxygen levels when you are not moving if background measurements are on. The device will only take blood oxygen measurements overnight if you are tracking sleep with your Apple Watch. You can disable these measurements if the sensor’s light disrupts your sleep.
How to take an on-demand measurement
Compatible Apple Watches also allow you to take blood oxygen measurements on demand. For an accurate reading, make sure your band is snug and that the back of your Apple Watch is touching your skin. Your watch should rest an inch or two above your wrist bone.
- Open the Blood Oxygen app on your Apple Watch.
- Rest your arms on a table, keeping your wrist and palm down and flat.
- Tap Start and keep still for the duration of the measurement.
- Tap Done. Visit the Health app on your paired iPhone to review your results.
Read more: Common Apple Watch problems and solutions
While Apple’s SpO2 monitoring is considered to be largely accurate, the Apple Watch is not intended to be used as a medical device.