Fitbit Charge 2Fitbit Charge 3
Tech specs 
SizeWidth: 21mm
Small: 14 cm - 17 cm in circumference
Large: 16.5 cm - 20.6 cm in circumference
XL: 20.6 cm - 23.6 cm in circumference
Device Dimensions: 35.8mm x 22.7mm x 11.8
One size (small and large bands included)
MaterialStainless steel casing, elastomer strapBuilt of more lightweight material including an aerospace grade aluminum case and Corning Gorilla Glass 3 display. The housing and buckle are made of anodized aluminum.
ChargingUSB. USB
Battery lifeup to 5 daysup to 7 days
Water-resistanceSweat, rain and splash proof.5 ATM
Weight36 grams29 grams
SensorOptical heart rate tracker, 3-axis accelerometer, altimeter, vibration motorOptical heart rate tracker, 3-axis accelerometer, altimeter, SpO2, vibration motor
DisplayOLEDOLED full touchscreen, TFT
Screen size3.8 cm35.8mm x 22.7mm
ColorsBlack, Plum, Blue, Teal, Lavender Rose Gold, Black/Gunmetal Multiple
OtherNFC (Special edition)
Connectivity: Bluetooth, WiFi
Charge 3 stores your stats and data for 7 days in between the times you sync your tracker.
Activity tracking 
Calories burnedYesYes
Heart rate24/724/7 + HRV (premium subscription)
Stress & recovery
Pulse OxYes
Respiration rateYes (premium subscription)
UV exposure
Skin temperature
Galvanic skin response
Hydration level
Calorie intake
GPSConnected GPSConnected GPS
Running features
Swimming features
Other Guided breathingGuided breathing, Female Health Tracking
Non-fitness functions 
Smartphone notificationsYesYes
On-board music storage
Connected payYes (special edition)
Affiliate link*Amazon | FitbitAmazon | Fitbit
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