Fitbit Sense 2 Health & Fitness Smartwatch – Blue Mist / Soft Gold Aluminum | FB521GLBM
Learn to manage stress & sleep better with our most advanced health & fitness smartwatch.
STRESS & SLEEP
All-day body-response tracking
EDA Scan app for stress management
Stress Management Score
Relax breathing sessions
Sleep tracking & sleep stages
Smart Wake alarm
SpO2 (blood oxygen) tracking
Irregular heart rhythm notifications
ECG app for heart rhythm assessment
Resting heart rate
High & low heart rate notifications
Heart rate variability
Skin temperature sensor
Blood glucose tracking (in app only)
Menstrual health tracking
Heart rate tracking
Daily Readiness Score
Active Zone Minutes
Steps, distance & calories
Cardio Fitness Score
Automatic exercise tracking
Workouts on your phone
SMARTS & MORE
Call, text and app notifications
On-wrist Bluetooth® calls
Find My Phone
Always-on display mode
Do not disturb & sleep mode
Compatible with iOS and Android devices
6+ day battery
Clock faces & accessories
Fitbit Premium membership
- Fitbit Sense 2
- Classic band (small & large)
- Charging cable
Sensors & Components
- Multi-path optical heart rate sensor
- Electrical sensor to measure skin conductance (cEDA) for body response tracking
- Multipurpose electrical sensors compatible with ECG app & EDA app. ECG not available in all countries.
- Red and infrared sensors for oxygen saturation (SpO2) monitoring
- 3-axis accelerometer
- Skin temperature sensor
- Ambient light sensor
- WiFi (deactivated, cannot be turned on)
- Built-in GPS + GLONASS
- Vibration motor
- Speaker (75dB SPL @10cm)
Battery & Power
- Battery life of 6+ days. Battery life and charge cycles vary with use, settings and other factors; actual results will vary. Use of the always-on display, SpO2 and the cEDA sensor will require more frequent charging. Up to 5 hours with continuous GPS. We recommend charging your tracker every few days to ensure you are always tracking.
- Battery type: Lithium-polymer
- Charge time (0-100%): Two hours
- Charge 12 minutes to get one day of battery life
- Radio transceiver: Bluetooth® 5.0
- Saves 7 days of detailed motion data, minute by minute
- Saves daily totals for the last 30 days
- Stores heart rate data at one-second intervals during exercise tracking and at five-second intervals all other times
Water resistant to 50m. After 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. Learn more.
Give your wrist a rest by taking the band off every now and then. If the band gets wet or you sweat in it, remove and completely dry the band before putting it back on. Learn more.
This watch includes a band made of a flexible material similar to that used in many sports watches, as well as an aluminum watch case and buckle.
Like all heart rate tracking technologies, accuracy is affected by physiology, location of device and different movements.
- Operating temperature: -14° to 113°F
The Fitbit app is compatible with most popular phones. To set up and use your Fitbit products and services, you must install the Fitbit app on a compatible device running one of the following operating systems:
- Apple iOS 14 or higher.
- Android OS 10 or higher. See additional tips for Android phones here.
Syncing range: Up to 30ft
- Certain features like smartphone notifications may require Android 10+. Check your device compatibility.
- Syncing requires Bluetooth® LE, an internet connection and location permissions granted on the phone
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
Large: Fits wrist 7.1″ – 8.7″ in circumference
- 1.5″ l x 1.5″ w x 0.45″ h