Fitbit Flex
Quick details
Released
May 2013
Dimensions
15.2 x 10.2 mm (width/thickness)
Operating system
Proprietary Fitbit firmware
Display 0.5 inch LED display
Battery life Up to 5 days
Water resistance Splash and rain resistant; not for swimming or showering
GPS No
Sensors 3-axis accelerometer, vibration motor
Technical specifications
General
Release date 2013-05-06
Product type Fitness tracker
Physical size 15.2 x 10.2 mm (width/thickness)
Weight 13.4 g with small band; 14.6 g with large band
Material Elastomer wristband; tracker with rechargeable lithium-polymer battery
Water resistance Splash and rain resistant; not for swimming or showering
Color options Black, Slate, Tangerine, Teal, Navy, Violet, Blue, Lime, Pink, Red
Display type 5-LED indicator
Display size No conventional screen
Display resolution Not applicable
Display brightness Peak brightness not published
Display protection Not applicable
Battery Rechargeable lithium-polymer battery
Battery life Up to 5 days
Charging USB charging cable
Charging time About 2 hours
Sensors
GNSS type None
GPS No
GALILEO No
GLONASS No
QZSS No
Beidou No
Accelerometer Yes
Gyroscope No
Barometric altimeter No
Compass No
Geomagnetic No
Ambient light sensor No
Optical heart rate No
Electrical heart rate No
SpO2 No
Temperature No
Galvanic skin response No
Microphone No
Speakers No
Vibration motor Yes
Health & activity tracking
Steps Yes
Distance Yes
Calories burned Yes
Floors No
Sports tracking Yes
Sleep Yes
Heart rate No
HRV No
Stress No
Blood oxygen No
Respiration rate No
Skin temperature No
ECG No
Blood pressure No
Body composition No
Glucose No
Hydration level No
UV exposure No
Calorie intake No
Daily Readiness No
Cardio Load No
Target Load No
Hyperglycemia risk assessment No
Arterial stiffness detection No
Pulse wave arrhythmia analysis No
Daily smart features
Smartphone compatibility Compatible iOS/Android devices via Fitbit app; Bluetooth 4.0
Operating system at launch Proprietary Fitbit firmware
Data retention 7 days detailed data; 30 days daily totals
Bluetooth Yes (4.0)
Wi-Fi No
NFC / connected pay No
UWB No
Cellular No
Smartphone notifications No
Bluetooth calling No
Smartphone music control No
On-board music storage No
Voice assistant No
Links
These technical specs are correct to the best of our knowledge at the time of publishing.
