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 6
Buyer's Guide: Apple Watch (Neutral)

Top Rated Comments

69Mustang Avatar
21 weeks 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
21 weeks 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
21 weeks 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)
Theyayarealivin Avatar
21 weeks ago
Well written and very helpful article. Good job Macrumors. Keep up the good work.
Score: 3 Votes (Like | Disagree)
BeefCake 15 Avatar
21 weeks 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
21 weeks 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)

Top Stories

2021 mbp sd slot feature2

Kuo: New MacBook Pro Models With HDMI Port and SD Card Reader to Launch Later This Year

Monday February 22, 2021 8:52 pm PST by
Apple plans to release two new MacBook Pro models equipped with an HDMI port and SD card reader in the second half of 2021, according to analyst Ming-Chi Kuo, who outlined his expectations in a research note obtained by MacRumors. The return of an SD card reader was first reported by Bloomberg's Mark Gurman last month. "We predict that Apple's two new MacBook Pro models in 2H21 will have...
m1 mac mini

M1 Mac Users Report Excessive SSD Wear

Tuesday February 23, 2021 7:07 am PST by
Over the past week, some M1 Mac users have been reporting alarming SSD health readings, suggesting that these devices are writing extraordinary amounts of data to their drives (via iMore). Across Twitter and the MacRumors forums, users are reporting that M1 Macs are experiencing extremely high drive writes over a short space of time. In what appear to be the most severe cases, M1 Macs are sai...
iphone 12 pro display video

BOE Rumored to Supply iPhone 13 Display Panels After iPhone 12 Failures

Monday February 22, 2021 9:54 am PST by
Display manufacturer BOE will be one of the main suppliers of OLED panels for iPhone 13 models, according to a new report today from Taiwan's Economic Daily News. BOE is said to be working with touch panel manufacturer General Interface Solution (GIS), part of the Hon Hai Group to develop OLED panels. Multiple iPhone 12 rumors suggested that BOE would supply some panels for the devices,...
mac security privacy

Apple Takes Step to Prevent Further Spread of 'Silver Sparrow' Malware on Macs

Monday February 22, 2021 6:13 am PST by
Over the weekend, we reported on the second known piece of malware compiled to run natively on M1 Macs. Given the name "Silver Sparrow," the malicious package is said to leverage the macOS Installer JavaScript API to execute suspicious commands. After observing the malware for over a week, however, security firm Red Canary did not observe any final payload, so the exact threat to users remains a...
jon prosser imac 2021colors

Prosser: 2021 iMac to Come in Five Colors, Apple Silicon Mac Pro to Resemble 'Stacked' Mac Minis

Wednesday February 24, 2021 7:26 am PST by
Hit-and-miss leaker Jon Prosser has today alleged that the upcoming 2021 iMac models will offer five color options, mirroring the colors of the fourth-generation iPad Air, and revealed a number of additional details about the Mac Pro with Apple Silicon. In a new video on YouTube channel FrontPageTech, Prosser explained that the redesigned iMacs will come featuring options for Silver, Space ...
whatsapp privacy banner

WhatsApp Reveals What Happens to Users Who Don't Agree to Upcoming Privacy Policy Changes

Sunday February 21, 2021 1:11 am PST by
WhatsApp has revealed how it will gradually limit the features available to accounts held by users who do not accept the platform's impending privacy policy changes, due to come into effect on May 15. WhatsApp's new banner explaining the privacy policy changes According to an email seen by TechCrunch to one of its merchant partners, WhatsApp said it will "slowly ask" users who have not yet...
new airpods leaked image 52audios

Alleged Leaked Image Claims to Show Third-Generation AirPods and Case

Sunday February 21, 2021 2:49 am PST by
A new image claims to offer our first real world look at Apple's next-generation AirPods. The image, shared by 52audio, showcases both AirPods and the charging case for what the site claims to be the third iteration of the wireless earbuds. 52audio has in the past shared images claiming to showcase different parts of the third-generation AirPods. Most notably, the site in November shared...
anker magsafe powercore battery pack

Anker Releases MagSafe-Compatible Battery Pack for iPhone 12 Lineup

Tuesday February 23, 2021 7:49 am PST by
Following rumors that Apple is working on a MagSafe battery pack for iPhone 12 models, popular accessory maker Anker has beaten Apple to the punch with the release of its PowerCore Magnetic 5K Wireless Power Bank. First previewed at CES 2021, the PowerCore battery pack magnetically attaches to the back of any iPhone 12 model and provides 5W of wireless charging. With a 5,000 mAh capacity,...
iPad Pro Mini LED

New iPad Pro and MacBook Models With Mini-LED Displays Again Rumored to Launch This Year

Monday February 22, 2021 9:32 pm PST by
Taiwanese company Ennostar will begin production of Mini-LED backlight units for an upcoming 12.9-inch iPad Pro in the late first quarter or second quarter of this year, according to industry sources cited by DigiTimes. Ennostar is a holding company that was jointly established in January 2021 by LED-related manufacturers Epistar and Lextar Electronics. Apple is expected to unveil the new ...
14

iOS 14.5 to Make Zero-Click Attacks 'Significantly Harder'

Monday February 22, 2021 9:05 am PST by
Apple's impending iOS and iPadOS 14.5 update will make zero-click attacks considerably more difficult by extending PAC security provisions, according to Motherboard. Apple has made a change to the way in which it secures its code in the latest betas of iOS 14.5 and iPadOS 14.5 to make zero-click attacks much harder. The change, spotted by security researchers, has now been confirmed by...