How to Use and Troubleshoot Blood Oxygen Monitoring on Apple Watch Series 6

Apple with the Apple Watch Series 6 introduced a new feature for monitoring blood oxygen level, using the LEDs at the back of the Apple Watch to determine the amount of oxygen in the blood. A low blood oxygen level can be indicative of a serious health issue that needs immediate attention.

apple watch series 6 blood oxygen monitoring 1
Taking a blood oxygen reading is rather straightforward, but there are automatic measurement settings to be aware of as well as necessary tips for getting an accurate measurement, all of which can be found in the guide below.

How Blood Oxygen Readings on Apple Watch Work

The Apple Watch Series 6 is equipped with green, red, and infrared LEDs that shine light onto the blood vessels in the wrist, with photodiodes measuring the amount of light reflected back.

series6leds 1
Apple's algorithms use this information to calculate the color of the blood, which is an indication of how much oxygen is in the blood. Bright red blood is well oxygenated, while darker blood has less oxygen.

The Apple Watch Series 6 can measure blood oxygen levels between 70 and 100 percent. Most healthy people have blood oxygen levels that range from 95 to 100 percent, though those with COPD and other lung diseases may have a lower average percentage.

series6leds
Apple does not expect the Blood Oxygen function in the Series 6 to be intended for medical use, and so the Apple Watch will not send a notification if a lower than normal blood oxygen level is detected.

Hardware Requirements

Using the Blood Oxygen monitoring feature requires an Apple Watch Series 6 running the latest version of watchOS along with an iPhone 6s or later with the latest version of iOS.

The Blood Oxygen app is available in almost all countries around the world, but if you're not seeing it, it might not be in your country. Apple has a list here.

Note that the Blood Oxygen app is not available to users under 18 and it is not enabled when an Apple Watch has been paired to an ‌iPhone‌ using Family Setup.

Enabling Blood Oxygen Measurements

When you set up a Series 6 Apple Watch, you'll be asked during the setup process if you want to enable Blood Oxygen measurements. If you tap "enable" when asked, the feature will be turned on automatically and will be usable through the Blood Oxygen app.

bloodoxygensetup

How to Take a Blood Oxygen Measurement on Apple Watch

  1. Make sure your Apple Watch Series 6 is snug but comfortable on your wrist.
    2blood oxygen app

  2. Open the Blood Oxygen app on your Apple Watch.
    3blood oxygen app

  3. Keep still, and make sure your wrist is flat with the Apple Watch facing upwards.
    blood oxygen app copy

  4. Tap Start, then keep your arm steady for 15 seconds.
    5blood oxygen app

  5. Wait for the measurement to be taken - you'll see the result when it's complete. Then tap Done.
    1blood oxygen app

You can view blood oxygen measurements taken over days, weeks, months, and years in the Health app on your ‌iPhone‌. Simply search for "Blood Oxygen."

bloodoxygenoniphone

Automatic Blood Oxygen Readings

In addition to on-demand readings, the Apple Watch Series 6 takes automatic blood oxygen readings throughout the day. Automatic blood oxygen measurements are enabled as long as Blood Oxygen Measurements are turned on and enabled, which is the default setting on the new Apple Watch.

Automatic blood oxygen readings are taken infrequently during the day, so you may only see these measurements a few times throughout your day, a departure from the frequency of heart rate measurements. Blood oxygen readings aren't taken as often simply because the wrist needs to be held still and in a specific orientation for a measurement.

Enabling Automatic Blood Oxygen Readings in Theater Mode

The Apple Watch has a Theater Mode that keeps the display of the Apple Watch dim to prevent it from being a nuisance in dark places like movie theaters, and there's a blood oxygen setting that can enable or disable readings during Theater Mode.

Apple says that blood oxygen readings require the use of a bright red light, which has the potential to be distracting in a dark room. Here's how to enable or disable readings in Theater Mode.

applewatchbloodoxygentheatermodesetting

  1. Open up the Settings app on the Apple Watch.
  2. Scroll down and tap on the Blood Oxygen app.
  3. Scroll down and tap the toggle next to "In Theater Mode" to turn the feature on or off.

Enabling Automatic Blood Oxygen Readings During Sleep

As with Theater Mode, Apple has an option to disable blood oxygen readings when the Apple Watch is in Sleep Mode because the bright light might be distracting in the dark. Here's how to enable or disable readings for Sleep Mode.

applewatchbloodoxygensleepmodesetting

  1. Open up the Settings app on the Apple Watch.
  2. Scroll down and tap on the Blood Oxygen app.
  3. Scroll down and tap the toggle next to "In Sleep Mode" to turn the feature on or off.

Viewing Blood Oxygen Data

No blood oxygen data can be viewed on the Apple Watch outside of the reading that you just took if you have the app open. Historical data needs to be viewed on the ‌iPhone‌, and it can be a little bit hard to find.

bloodoxygenoniphone
Here's the easiest way to get to your data.

  1. Open up the Health app on the ‌iPhone‌.
  2. Tap on Browse at the bottom of the app.
  3. Tap on Vitals or at the top of the app, search for Blood Oxygen.
  4. Tap on the reading that comes up.

From here, you can see your average Blood Oxygen measurements by day, week, month or year, tapping on the chart to see specific information about each reading in day view or ranges for the other view options.

bloodoxygensaturationweekly
Tapping on "Show More Blood Oxygen Data" provides the latest reading, range over time, daily average, and readings in a High Elevation Environment or during sleep if those apply.

If you scroll all the way to the bottom of the app, there's a "Show All Data" option that you can tap to see all of the blood oxygen measurements that have been taken with specific information on date, barometric pressure, and more.

bloodoxygenshowalldata

Turn Off Blood Oxygen Monitoring

Don't want to use blood oxygen monitoring at all? It can be disabled in the Settings app.

  1. Open up the Settings app on the Apple Watch.
  2. Scroll down and tap on the Blood Oxygen app.
  3. Tap on the toggle next to "Blood Oxygen Measurements" to turn the feature off.

If you want to reenable blood oxygen readings at a later date, just turn the toggle back on. It's enabled by default when you set up the Apple Watch, so the only reason you might need to enable it is if you've previously disabled it.

Blood Oxygen Troubleshooting

The sensors that measure oxygen level in the blood on the Apple Watch are highly sensitive and the reading will fail even if there's minor movement. If you're frequently getting an "Unsuccessful Measurement" warning, make sure to follow these steps.

  1. Hold your wrist flat and face up, with your fingers also resting open. Blood oxygen measurements will not work if the arm is hanging down or if your fingers are in a fist.
  2. Make sure the Apple Watch is snug against the wrist with a band that fits well and is not too loose or too tight.
  3. Make sure the Apple Watch is flat against the wrist and not impeded by the wrist bone. If it is over the wrist bone, adjust the positioning of the watch.
  4. For more stability, put your wrist on a table or flat surface such as your lap.
  5. Minimize all movement for 15 seconds. The stiller you are, the better.
  6. Don't tap or otherwise engage with the Apple Watch. A tap on the screen or touching the Digital Crown can cause minute movement that disrupts the reading.

If you're following all of the above steps and are still having trouble, Apple warns that there are a few scenarios that can cause poor readings.

  • Tattoos - Dark tattoos in the area where the sensors are located can cause the light that shines through the skin to measure oxygen level to fail to work properly. There's no fix for this, unless there's a non-tattooed wrist area available. Note that lighter tattoos may not interfere with the sensor, and it may also work with those that leave a good amount of skin visible.
  • Cold weather - If it's cold outside, it can affect how much blood flows through your arm at any given time, which in turn can cause blood oxygen measurements to fail.
  • Skin perfusion - Regardless of weather, sometimes the blood flowing through the skin is slower, and this can vary significantly from person to person. Skin perfusion is a factor in how well the blood oxygen measurements work.
  • High heart rate - If your heart rate is above 150 beats per minute at rest, the blood oxygen measurement feature will not work.
  • Motion - As mentioned above, blood oxygen measurements tolerate little to no motion at all, and arm position is a factor. Hold the arm straight with your fingers out and try not to move if you're having issues.

Guide Feedback

Have questions about blood oxygen monitoring on Apple Watch Series 6 or want to offer feedback on this guide? Send us an email here.

Related Roundup: Apple Watch Series 9
Buyer's Guide: Apple Watch (Neutral)

Top Rated Comments

69Mustang Avatar
46 months ago

Lol - if it isn’t for medical use, then what it is for?

A lot of people have benefitted from the other notifications and then seeking treatment. It is strange that they aren’t going to send notifications for this also.
Claiming medical use requires FDA testing and approval. An involved process that would have meant the feature wouldn't have been ready for AW6.

I would suggest NOT using it right now. I get readings that bounce from 86% to 100% back to back while my clip on finger sensor is sitting steady at 97-98. There's just no reason to trust any reading you get from the watch at this point. maybe it will get better in the future, but I feel bad for GP's getting calls about their O2 levels being low from this watch.
Dave2D had the same complaint: inaccurate reading. He suggested removing the watch from the wrist and taking the measurement against a finger. Supposedly increased his accuracy.
Score: 5 Votes (Like | Disagree)
rjp1 Avatar
46 months ago

Apple does not expect the Blood Oxygen function in the Series 6 to be intended for medical use, and so the Apple Watch will not send a notification if a lower than normal blood oxygen level is detected.
Lol - if it isn’t for medical use, then what is it for?

A lot of people have benefitted from the other notifications and then seeking treatment. It is strange that they aren’t going to send notifications for this also.
Score: 4 Votes (Like | Disagree)
gpwdeux Avatar
46 months ago

That is a little disappointing.
In its current form, it isn't medically viable and like another poster said, just a marketing gimmick. The average Joe would see no beneficial information from a notification, and for the ones who actually need to "monitor" it, they would never trust its readings over a FDA approved device.
Score: 3 Votes (Like | Disagree)
TheYayAreaLiving ?️ Avatar
46 months ago
Well written and very helpful article. Good job Macrumors. Keep up the good work.
Score: 3 Votes (Like | Disagree)
BeefCake 15 Avatar
46 months ago
This will be a great feature when it's monitoring all the time like the heart rate.
Score: 2 Votes (Like | Disagree)
Craiger Avatar
46 months ago
I would suggest NOT using it right now. I get readings that bounce from 86% to 100% back to back while my clip on finger sensor is sitting steady at 97-98. There's just no reason to trust any reading you get from the watch at this point. maybe it will get better in the future, but I feel bad for GP's getting calls about their O2 levels being low from this watch.
Score: 2 Votes (Like | Disagree)

Popular Stories

iOS 18 Siri Integrated Feature

iOS 18 Will Add These New Features to Your iPhone

Friday April 12, 2024 11:11 am PDT by
iOS 18 is expected to be the "biggest" update in the iPhone's history. Below, we recap rumored features and changes for the iPhone. iOS 18 is rumored to include new generative AI features for Siri and many apps, and Apple plans to add RCS support to the Messages app for an improved texting experience between iPhones and Android devices. The update is also expected to introduce a more...
iGBA Feature

Game Boy Emulator for iPhone Now Available in App Store Following Rule Change [Removed]

Sunday April 14, 2024 8:06 am PDT by
A week after Apple updated its App Review Guidelines to permit retro game console emulators, a Game Boy emulator for the iPhone called iGBA has appeared in the App Store worldwide. The emulator is already one of the top free apps on the App Store charts. It was not entirely clear if Apple would allow emulators to work with all and any games, but iGBA is able to load any Game Boy ROMs that...
iGBA Feature

Apple Removes Game Boy Emulator iGBA From App Store Due to Spam and Copyright Violations

Sunday April 14, 2024 9:22 pm PDT by
Apple today said it removed Game Boy emulator iGBA from the App Store for violating the company's App Review Guidelines related to spam (section 4.3) and copyright (section 5.2), but it did not provide any specific details. iGBA was a copycat version of developer Riley Testut's open-source GBA4iOS app. The emulator rose to the top of the App Store charts following its release this weekend,...
iOS NES Emulator Bimmy Feature

NES Emulator for iPhone and iPad Now Available on App Store [Removed]

Tuesday April 16, 2024 11:33 am PDT by
The first approved Nintendo Entertainment System (NES) emulator for the iPhone and iPad was made available on the App Store today following Apple's rule change. The emulator is called Bimmy, and it was developed by Tom Salvo. On the App Store, Bimmy is described as a tool for testing and playing public domain/"homebrew" games created for the NES, but the app allows you to load ROMs for any...
m3 mbp space black

M4 Macs Are Expected to Launch in This Order Starting Later This Year

Sunday April 14, 2024 10:40 am PDT by
Bloomberg's Mark Gurman recently reported that the first Macs with M4 series chips will be released later this year, with more models to follow next year. In his Power On newsletter today, Gurman shared a more specific roadmap for these Macs. Here is the order in which Gurman expects the Macs to launch:1. A low-end 14-inch MacBook Pro with the M4, coming around the end of 2024. 2. A 24-inch ...
iOS 18 Siri Integrated Feature

Apple's First AI Features in iOS 18 Reportedly Won't Use Cloud Servers

Sunday April 14, 2024 9:52 am PDT by
Apple's first set of new AI features planned for iOS 18 will not rely on cloud servers at all, according to Bloomberg's Mark Gurman. "As the world awaits Apple's big AI unveiling on June 10, it looks like the initial wave of features will work entirely on device," said Gurman, in the Q&A section of his Power On newsletter today. "That means there's no cloud processing component to the...
new best buy blue

Best Buy Opens Up Sitewide Sale With Record Low Prices on M3 MacBook Air, iPad, and Much More

Saturday April 13, 2024 7:41 am PDT by
Best Buy this weekend has a big sale on Apple MacBooks and iPads, including new all-time low prices on the M3 MacBook Air, alongside the best prices we've ever seen on MacBook Pro, iPad, and more. Some of these deals require a My Best Buy Plus or My Best Buy Total membership, which start at $49.99/year. In addition to exclusive access to select discounts, you'll get free 2-day shipping, an...