Many options exist when shopping for a smartwatch, including a few that let you measure blood oxygen level data throughout the day. Let’s preface this article with the truth that these measurements represent an estimate. You should not use them for medical purposes.

These smartwatches and fitness trackers offer blood oxygen monitoring because the information helps you determine the appropriateness of the intensity level of your workout or training session. Most people know the names Apple Smartwatch and Fitbit, but you have many other options for smartwatches that let you measure blood oxygen.

What Is My Blood Oxygen Level?

The term blood oxygen level, represented as SpO2, refers to the amount of oxygen saturation in the blood. In any human, this should measure 90% or higher. If your smartwatch reads 89% or less, immediately measure blood oxygen using a pulse oximeter to double-check the data. While smartwatches provide an estimate, you should double-check anything below 90%.

Health experts consider 95% or above to fall into the healthiest or good score range. Each smartwatch manufacturer defines normal range differently, so read the instructions and consult your doctor. You and your healthcare provider can test your smartwatch against a pulse oximeter at the doctor’s office to determine its rough accuracy.

This also provides your physician with an opportunity to explain the limitations of smartwatch health sensors and what you should do if you obtain a reading that falls below what the doctor says normal is for you.

If your SpO2 measures 88% or below, immediately get to an emergency room.

The hospital will use a pulse oximetry method that measures using an oximeter that fits on your finger or toe. Sometimes, they’ll use an oximeter that attaches to your head, but those prove rare.

Blood oxygen level naturally drops as you exercise. If you watch sports on TV, especially American football, you might spy a player donning an oxygen mask between plays. That’s because they can feel the difference in their blood oxygen level and know they need a boost.

Blood Oxygen Monitoring with a Smartwatch

Your Apple watch can measure blood oxygen but not with the same accuracy that pulse oximeters can. Use it to gauge your workout and help keep you on track. People who have COVID-19 or have recovered from it may also find value in a watch that measures their SpO2 since low oxygen saturation is common among those people with the virus.

Let’s consider the many choices offered by the smartwatch industry. Not every smartwatch offers SpO2 level measurement. The following are the best smartwatches for SpO2 levels:

Garmin Forerunner 245
Fitbit Versa 3
Garmin Vivoactive 4
Fitbit Sense
Garmin Fenix 6
Garmin Forerunner 945
HONOR Band 5
Huawei Band 4

Each of these devices uses a different method to measure blood oxygen, but they can take better measurements when you’re still and have watch bands that fit snuggly.

Using an Apple Watch for Pulse Oximetry

The Apple Series 6 Watch and those following it include SpO2 sensors, except the Apple Watch SE. Its design lets you take 15-second blood oxygen level spot-checks. This means it will monitor your blood oxygen levels while you sleep. You can enable the Apple Watch to monitor your blood oxygen information by doing the following:

Using your iPhone, open the Health app.
Choose the Browse tab.
Go to the Respiratory settings.
Choose Blood Oxygen.
Tap the Enable link.

Take these extra steps to set it up to do spot readings:

On your Apple Watch, open the Blood Oxygen app.
Tap the Start link.
Pause for 15 seconds.
Tap the Done link.

You can also turn on or off background readings on an Apple Smartwatch.

On your Apple Watch, open the Settings app.
Choose Blood Oxygen.
Tap the Blood Oxygen Measurements to turn it on or off. When on, it takes periodic daytime readings.
Use Sleep Focus to measure SpO2 while you sleep. Tap the Sleep Focus link to turn it on or off. (The electronic toggle switches from on to off and vice versa.)

Apple offers an In Theater Mode setting that lets you suspend the device’s measurements while you watch a film.

Using a Fitbit for Pulse Oximetry

In 2017, Fitbit added SpO2 sensors to The Ionic smartwatch. Most of its devices released from 2020 to the present include SpO2 sensors, but the Inspire 2 doesn’t track blood oxygen levels. Fitbit pre-activates this measurement, so you don’t have to set anything up. It monitors SpO2 from the moment you put on the watch.

When you first put on your Fitbit, sit down for about 15 minutes to let your body return to its normal resting state. This allows you to obtain your SpO2 baseline, which refers to the normal level of oxygen in your blood. Memorizing your baseline lets you know when your SpO2 plummets or rises out of line with your normal state.

Here’s how to check your SpO2:

In the Fitbit app, choose the Today tab.
Tap the button for Sleep.
Tap the sleep log date you want to view. This opens your Estimated Oxygen Variation graph for that date.

Fitbit Premium users have a variation on these instructions to access their data. Premium subscribers tap the tile for Restoration in the sleep log to open the EOV graph.

Some Fitbit devices let you view SpO2 trends with a Fitbit Premium subscription and updated device. This means you can view 24 hours of data at one time. The Fitbit devices that include this option include the Charge 4 and 5, Luxe, Sense, and Versa 2 and 3. Here’s how to check it:

Wear the Fitbit for at least 24 hours.
After 24 hours, sync your device.
In the Fitbit app, tap the Today tab.
Choose the Health Metrics button.
Tap the Oxygen Saturation (SpO2) link.

If you install the SpO2 clockface, you can view your SpO2 information on the watch.

Two Fitbit devices, the Sense and Versa 3, offer the option of background SpO2 readings. Access these readings in the SpO2 Tracker app.

Monitoring Blood Oxygen Levels with a Garmin Device

Garmin calls blood oxygen measurements Pulse Ox in its apps. The manufacturer lets its users determine how frequently to measure SpO2. View your blood oxygen levels using the Pulse Ox widget on devices that use it. Here’s how to spot-check your blood oxygen levels while you work out:

Open the device menu.
Open the Pulse Ox feature with a tap.
Sit still while it takes the measurement.

You can turn on or off blood oxygen tracking using the same method.

Open the Garmin Connect app on your Android or iPhone.
Select the settings menu. On Android, select the hamburger icon (three-bar icon) in the top left corner. On iOS, tap the More option on the bottom right.
Choose Garmin Devices.
Tap on Activity Tracking.
Choose Pulse Ox.
Use the toggle button to turn on or off Sleep Tracking or All-Day Tracking.

You access your blood oxygen data from sleep differently than the data for waking.

Open the Garmin Connect app on your Android or iPhone.
Select the settings menu. On Android, select the hamburger icon (three-bar icon) in the top left corner; On iOS, tap the More option on the bottom right.
Choose Garmin Devices.
Choose Health Stats.
Tap on Sleep.
Tap on Pulse Ox option.

This opens the information of the measurements the watch took while you slept.

You Can Measure Blood Oxygen Saturation with a Smartwatch

Since these watches don’t use medical-grade sensors, you still need to measure blood oxygen saturation information using a pulse oximeter. Your blood oxygen data offers invaluable health metrics that can help you maintain your health after illness or during training for an athletic event.

You can’t use one of these smartwatches as a replacement for medical-grade health sensors, though. You’ll still need FDA-approved pulse oximeters to take medically accurate measurements. Many companies make medical devices such as these for use at home. You simply clip it on your finger to measure your blood oxygen saturation. Let your smartwatch make monitoring your health easier, but don’t solely rely on it for medical information.