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 7
Buyer's Guide: Apple Watch (Caution)
Related Forum: Apple Watch

Top Rated Comments

69Mustang Avatar
24 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
24 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
24 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
24 months ago
Well written and very helpful article. Good job Macrumors. Keep up the good work.
Score: 3 Votes (Like | Disagree)
BeefCake 15 Avatar
24 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
24 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)

Related Stories

13 inch macbook pro m2 mock feature 2

There's a New 13-Inch MacBook Pro Coming, Here's What We Know

Friday February 18, 2022 2:23 pm PST by
Apple refreshes the MacBook Pro models on a regular basis, and in 2022, we could potentially see new versions of the 13-inch MacBook Pro and the higher-end 14-inch and 16-inch versions. Rumors suggest a new 13-inch model could come as soon as spring, while we haven't heard much at all about a refresh of the larger models given that they just launched in October 2021. For now, this guide...
Studio v Pro Feature Purple

Mac Studio vs. Mac Pro Buyer's Guide

Friday March 18, 2022 11:26 am PDT by
The all-new Mac Studio is now Apple's most powerful desktop computer, surpassing even the high-end Mac Pro. The Mac Studio also starts at $1,999, substantially less than the $5,999 starting price of the Mac Pro. So why is the more expensive Mac Pro still in the lineup and should you buy it over the new Mac Studio? Our guide helps to answer the question of how to decide which of these two...
MAsk On Face ID iOS 15

Face ID With a Mask: How It Works and What You Need to Know

Wednesday February 2, 2022 2:07 pm PST by
For many people, Face ID has been frustrating to use for the past two years because it doesn't work with a face mask, but that's changing in iOS 15.4, an update that's currently available to developers and public beta testers. iOS 15.4 adds Face ID with a Mask, letting you unlock your iPhone with Face ID even when your face is covered, so Face ID is as convenient with a mask as it is without ...
iPhone SE 2022 Red Feature

Everything We Expect to See From Tomorrow's Apple Event

Friday March 4, 2022 1:18 pm PST by
Apple is set to hold its first event of 2022 on Tuesday, March 8 at 10:00 a.m. Pacific Time. Apple's spring events sometimes aren't as exciting as the September and October events, but it's nice to have new devices on the horizon in the new year. Subscribe to the MacRumors YouTube channel for more videos. For the 2022 spring event, we're expecting a refreshed version of the iPhone SE, a new...
MAsk On Face ID iOS 15

iOS 15.4 Features: Everything New in iOS 15.4

Monday March 14, 2022 1:45 pm PDT by
Apple today released iOS 15.4 and iPadOS 15.4, the fourth major updates to the iOS 15 and iPadOS 15 operating systems that first came out in September. iOS and iPadOS 15.4 are huge updates that bring quite a few useful new features to the iPhone and the iPad. Subscribe to the MacRumors YouTube channel for more videos. Face ID With a Mask With iOS 15.4, there is now an option to unlock your...
Universal Control Colored Feature

Universal Control: Everything You Need to Know

Thursday February 3, 2022 1:48 pm PST by
iOS 15.4 and macOS Monterey 12.3 introduce Universal Control, a long-awaited feature that Apple first previewed at the 2021 Worldwide Developers Conference. Universal Control is designed to allow you to control multiple Macs and iPads with a single trackpad/mouse and keyboard, and this Universal Control guide covers the ins and outs of the feature and answers all the questions you might have ...
ipad pro vs air early 2022

iPad Air 2022 vs. iPad Pro 2021 Buyer's Guide

Wednesday March 9, 2022 1:59 pm PST by
In March 2022, Apple introduced the fifth-generation iPad Air, featuring the M1 chip, 5G connectivity, and a new front-facing camera system. The updated iPad Air comes almost a year after in Apple introduced its current iPad Pro lineup, which also features the M1 chip and 5G connectivity, but sports a number of high-end features like ProMotion and a Thunderbolt port. The introduction of the...
Apple Watch Series 7 Pink and Green Feature

Apple Watch Series 7 Rumors

Saturday September 4, 2021 10:03 am PDT by
Apple Watch Series 7 Announced! Apple announced the Apple Watch Series 7 in September 2021 alongside the new iPhones, and the Series 7 was a surprise because it did not match up with what we expected from rumors. Rumors indicated the Apple Watch Series 7 would feature a flat-edged design like the iPhone 13 models, but it does not. It continues to use a rounded body, but it is available in...

Popular Stories

Apple Watch Series 7 Starlight Midnight

Standard Apple Watch Series 8 Rumored to Feature Same Design as Series 7

Friday August 5, 2022 7:46 am PDT by
The standard 41mm and 45mm models of the Apple Watch Series 8 will feature the same design as the Apple Watch Series 7, according to Twitter user @ShrimpApplePro, who was first to reveal that iPhone 14 Pro models would feature a new pill-and-hole display. Titanium will not be an option for the standard Apple Watch Series 8 models either, according to @ShrimpApplePro, but Bloomberg's Mark...
iPhone 14 Pro Purple Front and Back MacRumors Exclusive

Five iPhone 14 Rumors You May Have Missed

Thursday August 4, 2022 6:05 am PDT by
With August upon us, the countdown is officially on. We're just weeks away from when we're expecting Apple to announce the iPhone 14 lineup. Rumors of the next iPhone start early in the year, and as a result, some details about the upcoming device sometimes get lost in the crowd. Exclusive MacRumors iPhone 14 Pro renders by graphic designer Ian Zelbo To help MacRumors readers, we've created a ...
oneplus 10t and iphone 13 pro

Camera Comparison: The New OnePlus 10T vs. iPhone 13 Pro Max

Wednesday August 3, 2022 8:30 am PDT by
Android-based smartphone company OnePlus today announced the launch of its newest device, the OnePlus 10T, which we were able to check out ahead of time. The OnePlus 10T, priced starting at $649, boasts upgraded camera technology, so we thought we'd pit it against the iPhone 13 Pro Max to see just how it measures up. Subscribe to the MacRumors YouTube channel for more videos. The OnePlus 10T...
banish safari app pop ups

New iOS App Blocks Those Annoying 'Open in App' Pop-Ups in Safari

Friday August 5, 2022 2:47 am PDT by
You've probably experienced visiting a website like Reddit or LinkedIn on your iPhone only to be greeted with an annoying, almost full-screen pop-up urging you to view the content in their app instead of on the website. It's a common practice for websites that have accompanying iOS apps to push users to open (if they already have the app installed) or download their app from the App Store to ...
apple watch series 7 titanium

Apple Watch Edition Begins Selling Out Ahead of Series 8 Launch

Tuesday August 2, 2022 7:55 am PDT by
Apple Watch Edition models are beginning to sell out just weeks before the Apple Watch Series 8 lineup is expected to be announced. Several of the high-end Apple Watch Series 7 models with titanium casings are listed as "currently unavailable" on Apple's online store in the United States, Canada, the United Kingdom, and select other countries. In the United States, availability of 41mm...