
How to Check Your Blood Oxygen Levels With the Apple Watch

By Andrew Myrick 0 comments Last updated September 25, 2020
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Apple is continuing to innovate in the smartwatch space, with just about every other smartwatch manufacturer having to play catch up. In fact, it’s difficult to find another option that works as seamless with your smartphone, let alone sports the feature-list as the Apple Watch Series 6.
What Apple Watch features Blood Oxygen Sensors?
When Apple originally launched the Apple Watch back in 2014, this marked a turning point for the company. In a Tim Cook-led regime, there was going to be more of a focus on the accessories to help make the iPhone and iOS experience even better. There weren’t too many health features available on the original Apple Watch, but since then, we have seen major additions with every iteration.
- (2016) Watch Series 2 – Built-in GPS / Water-resistance / Swim tracking
- (2017) Watch Series 3 – LTE connectivity / Built-in Altimeter
- (2018) Watch Series 4 – Fall Detection / Emergency SOS / ECG measuring
- (2019) Watch Series 5 – Magnetometer / Compass / Always-On Display
Just a few weeks ago, Apple unveiled the new Watch Series 6, with quite an impressive array of features. Not only is the Always-on Display brighter than the previous generation, but is a new health-sensor in-tow. The Blood Oxygen (SpO2) sensor can now read your SpO2 levels throughout the day. This provides another method for your Apple Watch to alert you if something is going on with your body that you weren’t aware of.
All of this means that if you are interested in the SpO2 measurements, the Apple Watch Series 6 is the right Watch for you. The new Watch SE has many of the same features of the Series 6, but lacks the proper sensors to measure blood oxygen levels.
How does the Blood Oxygen sensor work?
As one would expect, the new SpO2 sensor is built into the back of the Apple Watch, along with the other health sensors which rest on your wrist. When measuring your levels, there are four clusters of red, green and infrared LED lights, which work with four photodiodes to convert light into an electrical current. The lights shine onto the blood vessels in your wrist, with the photodiodes measuring how much light bounces back.
The color of your blood helps to determine how much oxygen is in your blood. Oxygenated blood is bright red, while dark red blood usually indicates that there’s less oxygen. If your blood does not have enough oxygen, it could mean that your lungs are not providing enough. If you’re concerned with the readings from your Apple Watch Series 6, be sure to call your health care professional and ask questions.
Getting started
Before you can begin taking advantage of the blood oxygen readings, you’ll need to ensure that the feature is enabled. By default, this should be turned on, but if you don’t see the Blood Oxygen app on your Apple Watch, here’s what you need to do:
- Open the Apple Watch app on your iPhone.
- Tap the My Watch tab at the bottom.
- Scroll down and select Blood Oxygen from the menu.
- Tap on the toggle next to Blood Oxygen Measurements to turn the feature on.
There are a couple of more settings available for checking your SpO2 levels with the Apple Watch. While you can actively choose to check your levels whenever the Apple Watch is also capable of taking readings in the background throughout the day. These are the other two options you may want to enable:
- Allow Background Measurements
- In Sleep Mode
- In Theater Mode
The only thing to consider, primarily in Theater Mode, is that a bright red light is emitted from the bottom of the Watch during readings. If you’re actually a movie theater and your Watch starts showing off that light, you may end up disturbing those around you.
How to check your Blood Oxygen Levels
Now for the moment of truth. After enabling the Blood Oxygen readings from your iPhone, you can fire up the app on your Apple Watch and take your first reading.
- Open the Blood Oxygen app on your Apple Watch.
- Ensure that your Apple Watch is snug, but comfortable, and isn’t loose on your wrist.
- Rest your arm on a table, make sure your wrist is flat, and the Apple Watch display is facing up.
- Tap Start.
- Hold your arm completely still for the duration of the 15-second countdown.
- View your results.
- Tap Done.
Your results will be shown immediately after the test has finished being administered. You can then tap the Done button to go back to the main screen. For reference, Apple states that “the majority of people have a blood oxygen level of 95 – 99%”. But again, if you have any concerns, reach out to your Health Care professional.
View your Blood Oxygen history
If you want to view the results of your Blood Oxygen measurements that were taken in the background, you can do so from the Health app. Here’s how you can view all of your SpO2 readings and history.
- Open the Health app on your iPhone.
- Tap on the Browse tab at the bottom.
- Scroll down and select Respiratory.
- Tap Blood Oxygen.
From here, you will be able to view the chart of your various SpO2 levels that were taken by the Apple Watch. At the top of the page, as with all pieces of data, there are options to view daily, weekly, monthly, or yearly readings at the top. Under the bar graph, selecting Show More Blood Oxygen Data will open a new panel in the Health app. This shows you when the latest reading was taken, along with your Range and Daily Average. Just tap Done in the top right-hand corner to be taken back to the main Blood Oxygen screen.

He has written for a variety of sites over the years, including iMore, Android Central, Phandroid, and a few others. Now, he spends his days working for an HVAC company, while moonlighting as a freelance writer at night.
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