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Fitbit Charge 4 update now shows blood oxygen level on your wrist

Fitbit Charge 4
(Image credit: Tom's Guide)

There's a reason the Fitbit Charge 4 is at the top of our best fitness trackers page. It's small, it has a large-ish screen, has GPS built in, and it costs just $150. Now, it's getting even better with the ability to show your blood-oxygen saturation on the band itself.

When the Fitbit Charge 4 launched a little over a year ago, it had the ability to monitor your blood oxygen levels (also known as SpO2) throughout the night, and presented the findings on a chart on the Fitbit app. With the latest firmware update (1.000.34), Charge 4 wearers will be able to view this information on their wrist.

Although blood-oxygen monitoring has been available on some more advanced GPS watches, it gained prominence this year when it was introduced on the Apple Watch Series 6, and was found to be a possible early indicator of COVID. 

Typically, a person's SpO2 levels should be between 95 to 100 percent, but many COVID patients saw their levels drop far below that. Still, Apple et. al were quick to say that their devices were not FDA-approved diagnostic tools for this condition. SpO2 levels can also be used as a way to see if someone has sleep apnea.

Other Fitbit devices with blood oxygen sensors include the Fitbit Ionic, the Fitbit Sense, and the Fitbit Versa series; all measure your blood oxygen levels while you sleep, to get the most accurate reading. 

In order to view your SpO2 levels on your wrist, you'l have to update the Charge 4 to the latest firmware. However, like other Fitbit devices, you will only be able to check your SpO2 levels from the previous night; other wearables, like the Apple Watch 6 and the Garmin fenix 6, let you check your blood oxygen levels at the moment you want. You'll also only be able to view a week's worth of data unless you sign up for Fitbit Premium, which costs $80 per year.

This firmware update is still being rolled out; when it's available for your device, you should see a notification in the Fitbit app.

Mike Prospero

Michael A. Prospero is the deputy editor at Tom’s Guide overseeing the smart home, drones, and fitness/wearables categories. When he’s not testing out the latest running watch, skiing or training for a marathon, he’s probably using the latest sous vide machine or some other cooking gadget.