Fitbit Charge 3Garmin Vivosport
Tech specs 
SizeDevice Dimensions: 35.8mm x 22.7mm x 11.8
One size (small and large bands included)
Width: 21.0 mm
Thickness: 10.9 mm
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.Case material: fiber-reinforced polymer
Lens material: chemically strengthened glass
BatteryLithium-polymerRechargeable lithium-ion
Battery lifeup to 7 daysGPS mode: Up to 8 hours
Smartwatch mode: Up to 7 days
Water-resistance5 ATMSwim
Weight29 gramsSmall/medium: 24.1 g
Large: 27.0 g
SensorOptical heart rate tracker, 3-axis accelerometer, altimeter, SpO2, vibration motorGPS, barometric altimeter, compass, accelerometer, heart rate
DisplayOLED full touchscreen, TFTsunlight-visible, transflective memory-in-pixel (MIP), 72 x 144 pixels
Screen size35.8mm x 22.7mm9.7 mm x 19.3 mm
ColorsMultipleSlate, Limelight, Fuchsia Focus
OtherNFC (Special edition)
Connectivity: Bluetooth, WiFi
Charge 3 stores your stats and data for 7 days in between the times you sync your tracker.
MEMORY: 7 timed activities, 14 days of activity tracking data
Activity tracking 
Calories burnedYesYes
Heart rate24/7 + HRV (premium subscription)Yes
Stress & recoveryYes
Pulse OxYes
Respiration rateYes (premium subscription)
UV exposure
Skin temperature
Galvanic skin response
Hydration level
Calorie intake
GPSConnected GPSYes
Running featuresPreloaded running profiles, GPS based distance/time/pace
Swimming features
Other Guided breathing, Female Health Tracking- all day stress tracking
- gym workout tracking
- music control, find my phone, etc.
- Built in apps for running, cycling, cardio, walking, strength training, rep counting, stair-stepper.
Non-fitness functions 
Smartphone notificationsYesYes
On-board music storage
Connected payYes (special edition)
Affiliate link*AmazonAmazon
Read moreReviewReview
*Disclosure: We are a professional review site that receives a small commission from sales of certain items, but the price is the same for you. See our affiliate disclosure page for more details.
**All tech specs and images on this page come from manufacturers. These may change over time as manufacturers sometimes update their devices. While we cannot guarantee absolute accuracy of information on this page, we promise to review this content regularly and do our best to bring you the most up-to-date information. To be absolutely sure of tech specs of a particular device, we recommend checking the manufacturer’s website.