It takes around one to two hours for a Fitbit to go from an empty charge to full charge. A full Fitbit battery lasts from three to seven days. Fitbit recommends frequent charging for short periods of time to prevent battery emptying.
The Fitbit indicates a low battery with an empty battery icon upon pushing a button. Once the battery is low, Fitbit automatically reverts to power-saving mode and stops turning on the display to conserve power. The device continues to collect data until it fully shuts down. The Fitbit charges on any powered base station, and an owner can charge it on a computer using a USB cord or a standard outlet using a wall-to-USB adapter.