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To enable Blood Oxygen, open Settings on a compatible Apple Watch, tap Blood Oxygen, then turn on Blood Oxygen Recordings if that setting is available. To take a reading, open the Blood Oxygen app, keep your wrist still and flat for the 15-second countdown, and review the result. On certain U.S. models, the paired iPhone analyzes the data and results appear in the Health app.
The feature works on Apple Watch Series 6 or later and all Apple Watch Ultra models, where available by country or region, and is designed for users at least 18 years old. Apple Watch SE and Apple Watch For Your Kids do not support it. Apple says the feature is for general fitness and wellness, not medical use. Apple’s availability and usage guidance explains regional, hardware, and safety limitations.
Check compatibility before troubleshooting
Blood Oxygen is supported on:
- Apple Watch Series 6 or later, subject to regional availability
- All Apple Watch Ultra models, subject to regional availability
It is not supported on:
- Apple Watch SE
- Apple Watch For Your Kids
- Users under 18
Availability depends on the country or region. If you are considering a watch, check the exact model and regional eligibility before buying; the relevant hardware is a compatible Series 6-or-later or Ultra model.
Important U.S. model limitation
For Apple Watch models purchased in the United States on or after January 18, 2024, with part numbers ending in LW/A or LS/A, blood oxygen data analysis is performed on the paired iPhone and results are viewed in Health. The experience requires the latest available iOS and watchOS. Check the precise part number rather than assuming the watch will display an analyzed result itself.
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Find the part number
- Open the Watch app on the paired iPhone.
- Tap My Watch > General > About.
- Find Model Number. The displayed value is the part number.
- Tap the value to reveal the five-digit A-number model identifier.
Apple documents this process in its Apple Watch model-number guide. If your U.S. part number ends in LW/A or LS/A, check the paired iPhone’s Health app for results.
How to enable Blood Oxygen recordings
- On the Apple Watch, open Settings.
- Tap Blood Oxygen.
- Turn on Blood Oxygen Recordings, if the setting is present.
Keep the paired iPhone and Apple Watch updated to the latest available iOS and watchOS versions.
If the Blood Oxygen setting or app is missing
Confirm that the watch is not an SE, the wearer is at least 18, and the feature is available in the watch’s country or region. If the app was deleted, search for Blood Oxygen in the App Store on the Apple Watch and install it again.
If the app remains unavailable after checking compatibility, region, and software, consult Apple’s Blood Oxygen support page for current availability guidance.
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How to take an on-demand Blood Oxygen reading
- Wear the watch snugly but comfortably, with its back touching your skin and sitting flush on top of your wrist.
- Open the Blood Oxygen app on the watch.
- Rest your arm on a table or in your lap, with your wrist flat and palm facing down.
- Tap Start.
- Remain still for the full 15-second countdown.
- When the measurement finishes, review the result and tap Done if that button appears.
Apple notes that a reliable reading may not be obtained every time, even in ideal conditions. For U.S. models ending in LW/A or LS/A, the paired iPhone analyzes the data, and the result is viewed in Health.
How to improve a reading or troubleshoot a failure
Movement, poor skin contact, wrist position, and reduced blood flow can make a reading difficult. Try these adjustments:
- Check the fit. The back of the watch should touch your skin and sit flush; the band should be snug but not too tight.
- Move the watch above the wrist bone. If the wrist bones interfere, move it about 2.5–5 cm farther up your arm.
- Keep your arm and wrist still and flat. Support your arm on a table or in your lap during the entire measurement.
- Try again if needed. Apple cautions that the watch may not get a reliable reading every time, even when you follow the instructions.
Tattoos or other conditions affecting skin contact may interfere with the sensor. Correct fit and placement matter; a replacement band is not required.
How to check saved Blood Oxygen results on iPhone
- Open the Health app on the paired iPhone.
- Open Respiratory.
- Tap Blood Oxygen.
Apple says you can filter readings by day, week, month, six months, sleep, and high-elevation environment. For eligible U.S. models ending in LW/A or LS/A, Health on the paired iPhone is where analyzed results appear.
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Background readings and sleep measurements
Apple Watch takes occasional background Blood Oxygen measurements when you are not moving; frequency depends on your activity. A bright red light from the watch’s back may be visible during a measurement.
To stop background measurements during Sleep Focus or Theatre Mode, open Settings on the watch, tap Blood Oxygen, and turn off the corresponding background option. Low Power Mode also turns off background Blood Oxygen measurements.
Sleep readings require Track Sleep with Apple Watch to be enabled. If overnight measurements are missing:
- Confirm Blood Oxygen Recordings is enabled.
- Confirm Track Sleep with Apple Watch is enabled.
- Check whether Sleep Focus, Theatre Mode, or Low Power Mode is affecting background measurements.
- Wear the watch with its back flush against your skin while sleeping.
- Check Health > Respiratory > Blood Oxygen for saved results.
Why a Blood Oxygen number is not a diagnosis
Apple says measurements taken with the Blood Oxygen app are not intended for medical use and are designed for general fitness and wellness. The watch is not a substitute for a clinically validated medical test or professional evaluation.
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Apple Support says the majority of people record values in the 95–100% range, while some people live normally with lower values; readings can also be slightly lower during sleep. This is general context, not a diagnostic threshold.
If you have symptoms or a persistent health concern, seek medical advice rather than relying on the watch to diagnose or monitor a condition.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Quick troubleshooting
| Problem | What to check |
|---|---|
| No Blood Oxygen app or setting | Check model, age, regional availability, and whether the app needs to be installed again from the Apple Watch App Store. |
| Reading does not complete | Check that the watch sits flush against skin, move it above the wrist bone if needed, support the arm, and remain still for 15 seconds. |
| U.S. model purchased on or after January 18, 2024 | Check the part number. If it ends in LW/A or LS/A, look for results in the paired iPhone’s Health app. |
| No background or sleep readings | Check Blood Oxygen Recordings, Track Sleep with Apple Watch, Sleep Focus, Theatre Mode, and Low Power Mode. |
| Unexpected result | Repeat the measurement with a proper fit and no movement. Do not treat the number as a diagnosis; seek medical advice for health concerns. |
FAQ
Can Apple Watch SE measure Blood Oxygen?
No. Apple Watch SE does not support Blood Oxygen measurements. The feature works on Apple Watch Series 6 or later and all Apple Watch Ultra models where available.
Why can’t I see the Blood Oxygen app?
Check that your model is compatible, the wearer is at least 18, and the feature is available in your region. If the app was deleted, search for it in the App Store on the Apple Watch and install it again.
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Why don’t I see Blood Oxygen results on my Apple Watch?
For U.S. models purchased on or after January 18, 2024 with a part number ending in LW/A or LS/A, the paired iPhone analyzes the data and results appear in Health. Otherwise, check compatibility, regional availability, and the measurement instructions.
How long does an Apple Watch Blood Oxygen reading take?
An on-demand measurement takes 15 seconds. Keep your arm and wrist still and flat for the full countdown.
Can I use an Apple Watch Blood Oxygen reading for medical decisions?
No. Apple says the feature is designed for general fitness and wellness, not medical use. Seek professional medical advice for symptoms or ongoing concerns.
The Bottom Line
Use a supported, region-eligible Apple Watch, turn on Settings > Blood Oxygen > Blood Oxygen Recordings if available, and hold your wrist still and flat for 15 seconds during an on-demand reading. Check saved results in Health > Respiratory > Blood Oxygen, especially if your U.S. model ends in LW/A or LS/A. Treat readings as wellness information, not a diagnosis.
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