Note: As of December 15, 2020, Fitbit Sense and Versa 3 users can now view their SpO2 trends over the past week without a Premium membership.

At Fitbit, we are always working to identify new ways we can tell you more about your body and your wellness with new and existing technology. As part of our ongoing feature development, we have introduced a new capability—an estimate of your blood oxygen saturation. We’re excited to announce that in select markets, you can access it through the free SpO2 Signature clock face on your smartwatch, so that you can track potential changes in your wellbeing.¹

Blood oxygenation is a crucial part of your body properly metabolizing the energy it needs to function at an optimal level. Our bodies distribute oxygenated blood to every part of our body—and SpO2 is the level of oxygen in your blood. 

Oxygen levels in blood tend to remain relatively constant, even during exercise and sleep. If the cardiorespiratory system is working and a person is breathing room air, typically most of the blood’s oxygen carrying capacity is used, so that blood oxygen saturation during the day is generally between 95 and 100 percent. When blood oxygen saturation levels are significantly lower than normal, it can be detrimental to the functioning of the body. 

Nighttime SpO2 is usually lower than daytime SpO2 due to the fact that the total amount of air you breathe in tends to drop during sleep. In general, SpO2 values during sleep are typically above 90 percent. Tracking SpO2 can help you be more aware of your oxygen saturation trends during sleep, which may help you learn when there may be an indication of important changes in your fitness and wellness. 

Of course, everyone’s oxygen levels are different. If you want to see your SpO2 trends over time, you’ll be able to view them in the new Health Metrics dashboard, available to Fitbit Premium members.²

There are several ways to evaluate the oxygen saturation in your blood. One method involves actually getting a sample of blood and using laboratory chemistry equipment to measure oxygen saturation, and while this is one approach, it is not practical for many uses. That’s why it became common to use pulse oximeters, which use optical techniques to non-invasively measure SpO2.

How does it work? Deoxygenated blood, which is returned to your lungs via your veins, is a slightly darker red color than the fully oxygenated blood in your arteries and arterioles (small blood vessels that bring oxygenated blood to your tissues). By using Fitbit sensors to measure the relative reflection of red and infrared light from your blood via your wrist, and seeing how it varies as your heart beats, we can estimate your SpO2 value. 

It’s important to note that Fitbit does not measure or display SpO2 values below 80 percent. Fitbit SpO2 data is not intended for medical purposes, nor is it intended to diagnose, treat, cure, or prevent any disease or condition. The data provided by Fitbit SpO2 is intended to be a close estimation of your blood oxygen saturation levels, but may not be precisely accurate. You should not use or rely on Fitbit SpO2 for any medical purposes. 

With the SpO2 Signature clock face, your Fitbit smartwatch (Fitbit Ionic, Versa family, and Fitbit Sense) will track your average SpO2 levels while you’re sleeping. To get started, install the SpO2 clock face, then go to sleep wearing your smartwatch with the clock face, and within about an hour of waking up, you’ll be able to see your average SpO2 and range. Plus, you can expect more SpO2 clock faces soon to come in 2020! 

If you have a Fitbit Premium membership, you will be able to check your trends in the Health Metrics dashboard.