Is the Blood Oxygen app (SpO2) not working on your Apple Watch? Let’s fix it

Can’t figure out or having trouble using or setting up the Blood Oxygen app on your Apple Watch? Keep getting errors like unsuccessful measurement?

If you want to see a measurement of your current blood oxygen, follow our quick guide to get this app working for you now and test out Apple’s new oximeter feature!

Related reading

How to get a SpO2 (blood oxygen saturation) reading on your Apple Watch 

First of all, the SpO2 features work only on Apple Watch Series 6 and above when paired with an iPhone that runs iOS 14 and above. You must also install the Blood Oxygen app on your Apple Watch. app icon for blood oxygen app on apple watch

If you own an older or different model (such as the Apple Watch SE,) you cannot get a blood oxygen reading because the watch does not include the required sensors. 

Update your watchOS and iOS to the latest versions

  • For your iPhone 6s or later to the latest version of iOS by going to Settings > General > Software Update
  • Update your Apple Watch Series 6 to the latest version of watchOS by going to the Watch app on your paired iPhone > My Watch > General > Software Update

SpO2 is for adults only, who pair their watch to their iPhone Apple's Blood Oxygen app with iPhone health app and apple watch

Additionally, Apple allows adults (18 years and above) to access The Blood Oxygen app. It is not available to anyone under 18.

And if you set-up an Apple Watch for anyone in your household or family group using Family Setup, Apple disables the Blood Oxygen app, regardless of the family member’s age.

For the SpO2 feature to work, your Apple Watch must pair to its own iPhone (not a family member’s) and to your iCloud account.

Check if your country supports the blood oxygen app

Not all countries and regions support the Apple Watch blood oxygen app. When it’s not supported, you see a message letting you know. Apple watch blood oxygen app not available in your country and region

To review the latest list of countries to do offer this feature, visit this Apple support document. Apple updates this list as new countries and regions start to support SpO2 on Apple Watch.

How to set up and start the Blood Oxygen app for Apple Watch

Apple uses your iPhone’s Health app to sync data with the Blood Oxygen app on your iPhone.

So, if you never set-up the Health app on your iPhone, start there.

Set up your Health Profile on your iPhone using the Health app

  1. Open the Health app and tap the Summary tab
  2. Choose your profile picture or icon 
  3. Tap Health Profile > Edit
  4. Add information like gender, height, weight, and age, and so forth. Then, tap Done

Set up your Apple Watch to monitor SpO2 turn on blood oxygen measuring using Apple's Health app on iPhone

  1. Using the Health app on your iPhone
    1. Open the Health app
    2. Look for a prompt on-screen to set up Blood Oxygen, tap it, and follow the steps on-screen to set up Blood Oxygen Measurements
      1. If you don’t see the prompt, tap the Browse tab > Respiratory > Blood Oxygen > Set up Blood Oxygen
    3. After setup, look for the Blood Oxygen app on your Apple Watch
    4. If you don’t see the Blood Oxygen app on your Apple Watch, open the App Store on your Apple Watch for Blood Oxygen, and install it
  2. Using the Watch app on your iPhone
    1. Scroll down the list of apps and tap Blood Oxygen
      1. If you don’t see the Blood Oxygen app in the list of watch apps, open the App Store on your Apple Watch for Blood Oxygen, and install it
    2. Tap Enable
    3. Toggle on Blood Oxygen Measurements
      1. When turned on, your watch takes automatic blood oxygen readings throughout the day Blood oxygen app settings using Apple Watch app on iPhone
    4. Choose additional features, like turning on or off background measurements during sleep or while the watch is in theatre mode
      1. Blood oxygen measurements work in sleep mode only if you turn on Track Sleep with Apple Watch

settings for blood oxygen app on apple watchYou can also change the Blood Oxygen app settings anytime on your Apple Watch via Settings app > Blood Oxygen.

How to manually take a SpO2 measurement on your Apple Watch

You can manually begin a SpO2 reading on your device at any time. 

For the blood oxygen app to work on Apple Watch, keep watch snug and contacting skin directly

First, check that your watch is snug, not loose on your wrist–pushing it up towards your elbow 1 to 2 inches often helps the sensors get a good reading.

  1. Tap to open the Blood Oxygen app on your Apple Watch Blood oxygen app on Apple watch screen
  2. Place your wrist flat on a table or similar with your Apple Watch facing up and stay still
  3. Tap Start and keep your arm steady for the reading Start a blood oxygen SpO2 measurement on apple watch manually
  4. Wait for your Watch to take your measurement. You see a countdown on-screen–keep still this entire time
  5. If successful, you see your results on-screen 
  6. Tap Done to save the reading to your Health app save blood app results on apple watch to health app

Want to review your SpO2 readings?

You cannot see previous measurements on your Apple Watch, so you need to use the Health app on your iPhone to review your blood oxygen measurement history. where to find blood oxygen data in the Health app on iPhone

  1. Open up the Health app on your iPhone
  2. Tap Browse > Vitals > Blood Oxygen or Browse > Respiratory > Blood Oxygen
  3. To see more specific data, tap on a specific measurement or day 

Wondering about the accuracy of your watch’s SPo2 reading?

A new study indicates that the Apple Watch does a pretty good job of reading your blood oxygen levels.

See this article for more: New Study shows the efficacy of SpO2 readings on the Apple Watch.

Getting “Unsuccessful Measurement” errors when using the Blood Oxygen app on your Apple Watch? Blood oxygen app on apple watch unsuccessful measurement

The accuracy of the Blood Oxygen app varies based on your blood flow, where you place your Apple Watch on your wrist, where and how you place your hand for the reading, and how still you are when taking a measurement.

Your Apple Watch takes your blood oxygen level by shining light into your skin and checking how much of that light your body absorbs. sensors on Apple watch for blood oxygen and heart

So, if your watch is unable to get a reading, it likely means that something is interfering with the sensor’s ability to send light or interpret how light is absorbed.

If the Blood Oxygen measurement fails, try moving the watch higher up on your arm, an inch or two above your wrist. Wear the device above your wrist bone.

You also want the watch to fit snuggly around your skin, but not to the point where it’s digging into the skin. 

If you have tattoos or thick scars, try to find an area where the skin is even and not tattooed. 

Getting a blood oxygen measurement but are inaccurate or vary too much between reading?

If you’re seeing some readings within the normal range of 95-100% but then get a few outliers, like 80% or even lower, try a different method.

Instead of using your wrist, take your Apple Watch off and try a finger measurement.

Place the Apple Watch’s sensors in close contact with your finder pad and then wait for the countdown. See if you get better results this way!

Other tips to aide with taking a SpO2 measurement using the Blood Oxygen app

  • Make sure you lay your hand face-up with fingers spread open on a flat surface, like a table for the duration of the reading. Do not let your arm hang down
  • Keep still during the reading–moving or squirming around causes measurements to fail
  • Do not engage with any other activity on your watch or on any other device (like your iPhone)–any movement disrupts the reading
  • Try the other arm. Switching arms may also help yield better reading
  • Try lifting the arm wearing the device to heart level and hold it flat with fingers spread at heart level for 15 seconds and see if you get a reading

How to add Blood Oxygen complication to your Apple Watch face

To get a quick snapshot of your SpO2, add the Blood Oxygen app as a complication to your watch face.

  1. Press and hold on your Apple Watch’s face
  2. Tap Edit
  3. Swipe left all the way to the last screen to see all complications
    1. If you don’t see any, then that watch face does not support complications
  4. Tap a complication you want to replace
  5. Turn the Digital Crown and scroll through the list and choose Blood Oxygen to add it add blood oxygen app to apple watch complication

Need to monitor your lung health? Don’t rely on Apple’s Blood Oxygen app alone

While Apple’s Blood Oxygen app measures your oxygen saturation, it’s not currently FDA approved and cannot claim to diagnose or treat any medical conditions.

To claim a device as medical use requires FDA testing, approval, and clearance. Something Apple did not pursue for its SpO2 Apple watch feature.

Instead, the app is marketed as a wellness tool to help you determine how your body is responding to exercise and stress.

Apple’s blood oxygen readings aren’t as accurate as a medical device and have not been validated

Apple intends users to use this feature as another way to gauge overall health and fitness, not to treat, diagnose, or monitor specific health conditions.

Need to monitor medical conditions? Ask your doctor or use an FDA approved medical grade device

For folks that need to keep an eye on their blood oxygen and/or require supplemental oxygen, it’s best to ask your doctors for their recommendations. 

Or purchase a pulse oximeter that is approved by the FDA as a Class II Medical Device (verify that the product is approved for medical use, is medical device, or FDA cleared.)

Be careful, most pulse oximeters are classified just like the Apple Watch as a wellness product

When purchasing a pulse oximeter, check that it’s listed as a medical device. If not apparent, look for the legal disclaimer.

If you see this wording, “not a medical device, intended for sports and aviation use, not intended for medical use, should not be used for any medical purpose or any medical condition or designed for sports enthusiasts, aviators, bikers, mountain climbers” then it is not FDA approved.

Think of your Apple Watch as a companion to your medical device(s) 

You can still use the Apple Watch and its Blood Oxygen app as a helping hand to the tools or practices your physicians recommend.

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A. Beth Whittenberger
I started my love affair with computers way back in elementary school with the Apple II. Since then, I've worked with technology in my career as a media educator and videomaker. I have an MFA in media making from Temple University, where I also taught undergrads as an adjunct faculty member. Additionally, I was a writer, content producer, and editor on the popular tech blog AppleToolBox. So I know a thing or two about teaching others and creating how-to guides! After a cancer diagnosis, I turned to mobile technology like my Apple Watch to help me monitor my health throughout my chemotherapy treatment and later, to regain my wellness once in remission. I love sharing how to understand and use mobile tech, like smartwatches and phones, as a tool for empowerment to live our best and healthiest lives! Connect with me on LinkedIn!


  1. A great and helpful piece that helped me troubleshoot.

    In my case: “Cinema mode” prevented readings and I had started to use this at night but was puzzled over not getting readings. Enabling O2 readings with Cinema Mode. Fixed it.


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