Battery & Power Battery life up to 7 days, or up to 5 hours with continuous GPS use. Battery life and charge cycles vary with use, settings, and other factors; actual results will vary. We recommend charging every few days to ensure you’re always tracking.
Battery type: Lithium-polymer Charge time (0-100%): Two hours Radio transceiver: Bluetooth 4.0 Memory Saves 7 days of detailed motion and heart rate data, minute by minute Saves daily totals for past 30 days Measures heart rate data at 1-second intervals during exercise tracking and at 5-second intervals all other times
Water Resistance Water resistant to 50 meters. After swimming or getting the band wet, we recommend drying the band because, as with any wearable device, it's best for your skin if the band is clean and dry. We do not recommend wearing Fitbit Charge 4™ in a hot tub or sauna. Learn more.
Materials This tracker includes a plastic resin case and the band includes a stainless steel buckle. The classic band is made of a flexible, durable material similar to that used in many sports watches. The woven band is made from a comfortable polyester. Heart Rate Like all heart rate tracking technologies, accuracy is affected by physiology, location of device and different movements.
Band Size Print this guide to find the right size for you. Both small and large sizes included in box. Small Fits wrist 5.5" - 7.1" in circumference Fits wrist 140 mm - 180 mm in circumference Large Fits wrist 7.1" - 8.7" in circumference Fits wrist 180 mm - 220 mm in circumference Dimensions 1.4in l x 0.9in w x 0.5in h 35.8mm l x 22.7mm w x 12.5mm