Syncing your Fitbit device to your iPhone or Android smartphone is the fastest and easiest way to send your latest fitness activity to your Fitbit account.
After you download the official Fitbit app and do the initial setup on your phone, your Fitbit tracker routinely syncs to your smartphone in the background. You usually don't need to manually sync your data. If you want to manually sync your Fitbit with your smartphone—perhaps to meet a Fitbit Challenge deadline so you can add your activity before the Challenge ends—here's what you do.
Turn on your Fitbit tracker.