The most common reason your Fitbit won't sync is a broken connection between your device and your phone

Fitbit syncing fails most often because Bluetooth is turned off, the app has lost permission to use Bluetooth, or your phone and device are too far apart. Less commonly, the Fitbit battery is dead, the app needs an update, or your phone's operating system has changed permissions without warning. The fix usually takes under five minutes and involves toggling Bluetooth off and on, closing and reopening the app, or restarting your phone.

Syncing is how your Fitbit sends the steps, heart rate, and sleep data it collected to the Fitbit app on your phone, where you can see your stats and trends. If syncing stops, your device keeps recording data, but you cannot see it until the connection works again. The data does not disappear—it waits on the device until sync succeeds.

Key Takeaways

  • Turn Bluetooth off and back on in your phone's settings, then open the Fitbit app and tap the sync button—this fixes roughly half of all sync problems.
  • Close the Fitbit app completely and reopen it, because the app sometimes gets stuck in a state where it cannot reach your device even though Bluetooth is working.
  • Check that the Fitbit app has permission to use Bluetooth in your phone's settings, because iOS and Android updates sometimes revoke permissions without telling you.
  • Restart your phone and your Fitbit device if the above steps do not work, because this clears temporary glitches that survive app closures.
  • If your Fitbit battery is below 5 percent, charge it for at least 15 minutes before trying to sync, because a dying device cannot maintain a Bluetooth connection.

Check Bluetooth and restart the connection

Open your phone's settings and look for Bluetooth. On most Android phones, swipe down from the top of the screen twice to open the quick settings panel, then tap Bluetooth to turn it off. Wait five seconds, then tap it again to turn it back on. On iPhone, go to Settings, tap Bluetooth, and toggle it off, then on.

Once Bluetooth is back on, open the Fitbit app. Look for a sync button—on most Fitbit apps it is a circular arrow icon, usually at the bottom of the screen or in the top right corner. Tap it and wait 10 to 30 seconds. Your device should appear in the app and show a checkmark when sync completes. If nothing happens after 30 seconds, move to the next step.

Force close the Fitbit app and reopen it

The Fitbit app sometimes gets stuck waiting for a Bluetooth signal that never comes, even though Bluetooth itself is working. Closing the app completely and reopening it clears this stuck state. On Android, go to Settings, tap Apps, find Fitbit, tap it, and tap Force Stop. On iPhone, swipe up from the bottom of the screen (or swipe down from the top right on newer models) to open the app switcher, find the Fitbit app, and swipe it up to close it.

Wait 10 seconds, then open the Fitbit app again from your home screen. Tap the sync button and wait 30 seconds. This step works because the app restarts fresh and re-establishes the Bluetooth connection from the beginning.

Verify the Fitbit app has Bluetooth permission

Your phone's operating system controls which apps can use Bluetooth. If an update changed your settings or you denied permission when first installing the app, the Fitbit app cannot connect even though Bluetooth is on. On Android, go to Settings, tap Apps, find Fitbit, tap Permissions, and make sure Bluetooth is toggled on. On iPhone, go to Settings, scroll down to find Fitbit, tap it, and check that Bluetooth is set to Allow.

After you turn on permission, close the app completely and reopen it. The app will now be able to see your Fitbit device. Tap the sync button and wait for the connection to complete.

Restart your phone and your Fitbit device

If the above steps have not worked, restart both devices. Power off your phone completely—on most phones, hold the power button until a shutdown menu appears, then tap Shut Down or Power Off. Wait 10 seconds, then turn it back on. While your phone restarts, hold the button on your Fitbit device for 10 to 15 seconds until you see the Fitbit logo on the screen, then release. This restarts the device.

Once both devices are back on, open the Fitbit app and tap the sync button. A full restart clears temporary software glitches that survive app closures and Bluetooth toggles. Most sync problems that reach this point are resolved by a restart.

Check your Fitbit battery level

A Fitbit with a battery below 5 percent cannot maintain a stable Bluetooth connection. If your device has not synced in several days or you have not charged it recently, plug it into a USB charger using the cable that came with it. Charge for at least 15 minutes before trying to sync again. You do not need to charge it fully—just enough to get the battery above 5 percent.

While charging, you can check the battery level in the Fitbit app. Open the app, tap your profile icon, select your device, and look for the battery percentage. If it shows below 5 percent or does not show a number at all, the device is too low to sync. Charge for another 10 minutes and try again.

Update the Fitbit app if you have not done so recently

Fitbit releases updates that fix sync bugs and improve Bluetooth stability. If you have not updated the app in several months, an older version may have trouble connecting to newer Fitbit devices or phones running the latest operating system. On Android, open the Google Play Store, tap your profile icon in the top right, tap Manage Apps and Device, find Fitbit, and tap Update if an update is available. On iPhone, open the App Store, tap your profile icon, scroll down to find Fitbit, and tap Update.

After the update finishes, close the app completely and reopen it. Tap the sync button and wait 30 seconds. Updated versions often fix connection problems that older versions could not solve.

Frequently Asked Questions

How long does a Fitbit sync usually take?

A normal sync takes 10 to 30 seconds once the Bluetooth connection is established. If the sync button is still spinning after one minute, the connection has failed and you should try the troubleshooting steps above.

Will my Fitbit data be lost if it does not sync for a week?

No. Your Fitbit stores data on the device itself for several weeks. Once you fix the sync problem, all the stored data will transfer to the app. You will not lose any steps, heart rate, or sleep information.

Can I sync my Fitbit to more than one phone?

Your Fitbit can sync to one phone at a time. If you want to switch to a different phone, you need to unpair the device from the old phone first. In the Fitbit app, tap your profile, select your device, and look for an Unpair or Remove Device option.

What if my Fitbit is too far from my phone to sync?

Bluetooth typically works within 30 feet. If your phone is in another room, move it closer to your Fitbit and try syncing again. Once sync completes, you can move the phone away—the data stays in the app.

Does my Fitbit need to be connected to WiFi to sync?

No. Fitbit syncs over Bluetooth, not WiFi. Your phone does not need an internet connection for the sync itself to work, though you need internet to see your data in the app or upload it to Fitbit's servers.