Fitbit Charge 3Fitbit Versa
Tech specs 
SizeDevice Dimensions: 35.8mm x 22.7mm x 11.8
One size (small and large bands included)
Dimensions: 39.36 x 37.65 x 11.2mm
Large: Fits wrists 180 mm - 220 mm in circumference
Small: Fits wrists 140 mm - 180 mm in circumference
MaterialBuilt 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.The Fitbit Versa classic band is made of a flexible, durable material similar to that used in many sports watches, and includes an aluminum watch case and buckle.
Battery lifeup to 7 days4+ days. Charge time (0-100%): 2 hours.
Water-resistance5 ATMup to 50 metres (swim-proof) - 5 ATM
Weight29 grams38 grams
SensorOptical heart rate tracker, 3-axis accelerometer, altimeter, SpO2, vibration motor3-axis accelerometer, 3-axis gyroscope, optical heart rate monitor, altimeter, ambient light sensor, vibration motor, Pulse Ox, wi-Fi antenna (802.11 b/g/n), NFC (some versions)
DisplayOLED full touchscreen, TFTHi-res touchscreen (up to 1000 nits). Corning Gorilla Glass 3 display. 300x300 pixel resolution.
Screen size35.8mm x 22.7mm1.34 inches
ColorsMultipleComes in a number of different versions
OtherNFC (Special edition)
Connectivity: Bluetooth, WiFi
Charge 3 stores your stats and data for 7 days in between the times you sync your tracker.
- Saves 7 days of detailed motion data – minute by minute.
- Saves daily totals for past 30 days
Activity tracking 
Calories burnedYesYes
SleepYesYes (light, deep & REM)
Heart rate24/7 + HRV (premium subscription)Yes + HRV (premium subscription)
Stress & recovery
Pulse OxYesYes
Respiration rateYes (premium subscription)Yes (premium subscription)
UV exposure
Skin temperatureYes (premium subscription)
Galvanic skin response
Hydration level
Calorie intake
GPSConnected GPS
Running features
Swimming features
Other Guided breathing, Female Health Tracking- Guided breathing sessions
- Female health tracking
Non-fitness functions 
Smartphone notificationsYesCall, text and calendar notifications
On-board music storageYes, 2.5GB (300 songs) + access Pandora
Connected payYes (special edition)Yes
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