Google Fitbit Sense FB521, Black Dial, Grey Silicone Strap
Google Fitbit Sense, Black Dial
Fitbit Sense 2 is a square smartwatch with ECG, stress tracking, built-in GPS, an aluminium case and 50m water resistance.
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About this item
- Advanced health and fitness smartwatch built to help manage stress and sleep better
- All-day stress detection with cEDA, ECG app and SpO2 for deeper health insight
- Sleep Score, sleep stages and smart wake alarm to improve nightly rest
- Built-in GPS, 40+ exercise modes and 24/7 heart rate tracking
- Bluetooth calls, texts, Alexa built-in and 6+ day battery life
Top Highlights
- Brand
- Google Fitbit
- Model Name
- Fitbit Sense 2
- Model Number
- FB521
- Department
- Men
- Item Type
- Smart Watch
- Manufacturer
- Fitbit Inc
- First Available
- 23 September 2022
- Release Year
- 2022
Features & Specs
- Display
- LCD
- Additional Features
- Activity Tracker, Stress Tracking, Sleep Monitor, ECG, Heart Rate Monitor, GPS, Notifications, Phone Call, Text Messaging, Bluetooth
- Case Material
- Aluminum
- Case Thickness
- 12.35 mm
- Weight
- 190.5 g
- Water Resistance
- 50 m
- Sport Type
- Fitness
- Strap
- Silicone
- Clasp
- Buckle
- Closure Type
- Buckle
- Crystal
- Gorilla Glass 3
- Dimensions
- 3.99 x 1.19 x 3.99 cm; 190.51 g
Style
- Style Name
- Modern
- Dial Shape
- Square
- Dial Colour
- Black
- Band Color
- Grey
- Collection
- Sense
Description
Fitbit Sense 2 is a health-focused smartwatch aimed at people who want to understand stress, sleep and daily activity from one device on the wrist. It comes in Shadow Grey with a square display and a silicone strap.
The case is aluminium and the strap closes with a buckle. Water resistance is rated to 50 metres, and the watch includes built-in GPS, Bluetooth, an ECG app, heart rate monitoring and SpO2 measurement.
A standout feature is all-day stress detection with cEDA, paired with a daily Stress Management Score. With 40+ exercise modes, Sleep Score and a battery rated at 6+ days, it works as a daily companion for fitness and wellness tracking.
Frequently Asked Questions
Can I swim with the Fitbit Sense 2?
Yes for pool swimming. It is rated to 50 metres of water resistance, which suits lap swimming, showers and rain. It is not designed for diving or high-speed water sports, so keep it off those activities. Rinse it with fresh water after chlorine or salt exposure.
Does it track stress and sleep all day?
It uses cEDA for all-day stress detection and gives a daily Stress Management Score. For sleep it records sleep stages and a Sleep Score, and includes a smart wake alarm and do not disturb mode, so you get both daytime and overnight insight from one watch.
Will it work for running and gym sessions?
Built-in GPS lets you leave your phone at home on runs, and there are 40+ exercise modes with automatic exercise tracking. The Fitbit Sense 2 also shows a workout intensity map and Active Zone Minutes, which suits everyday sport and gym training.
How does it differ from a regular quartz watch?
A quartz watch tells time with a battery and gears, while this one is a digital smartwatch with a square LCD display. Compared with a classic watch, it adds ECG, SpO2, GPS and Alexa, but you trade the look and longevity of traditional materials.
How long does the battery last and can it make calls?
Battery life is rated at 6+ days, though GPS and heavy use shorten that. Calls, texts and phone notifications come over Bluetooth, so the phone must be nearby. Charging is needed regularly, which is a different routine from a quartz battery swap.
Is it suitable for a small or large wrist?
The watch is about 1.57 inches across with a silicone strap, so it suits a wide range of wrist sizes. Check that the strap length fits your wrist before buying. Its weight of roughly 190 grams as packaged includes the strap.
Editor's take
Fitbit Sense 2 sits at the wellness end of the smartwatch market, built for people who care more about stress, sleep and recovery data than about traditional watchmaking. It is a square, aluminium cased smartwatch with a silicone strap, released in 2022 as part of the Sense line.
Its most distinctive feature is cEDA stress detection, which runs through the day and feeds a daily Stress Management Score. Alongside it you get an ECG app, SpO2 measurement and built-in GPS, which together cover most of what a health-minded wearer will ask of a device on the wrist.
The trade-off is durability and water use. At 50 m water resistance it is fine for swimming in a pool, but it is not a dedicated dive or open-water instrument, and an aluminium case will pick up marks more easily than steel. The buckle closure is simple and practical, yet it offers none of the refinement of a metal bracelet.
It suits anyone who wants a single device for stress, sleep and daily training. Those wanting a more rugged outdoor tool could look at a dedicated GPS sports watch, whilst traditional watch fans will find a quartz or automatic piece fits better.
In categories
From the manufacturer
Understand stress, then minimise its effects.
Identify patterns of stress with all-day body response tracking, and try ways of managing it.[1]
Aluminium Case, Gorilla Glass 3
The Sense 2 pairs an aluminium case with Gorilla Glass 3 over the display, a sensible combination for a watch that sees daily wear. Aluminium keeps weight low on the wrist, while the glass resists the scratches that come from desks, door frames and gym equipment.
Silicone Strap for Daily Wear
The silicone strap is soft, light and unfazed by sweat, which suits a watch meant to stay on through workouts and sleep. It dries quickly after a shower or swim and is easy to wipe clean. Wearing it around the clock makes the sensor data more complete.
Personal coaching that’s built with Gemini.
See your tracking transformed with AI-powered coaching in the Google Health app.[7]
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Rated to 50 Metres
With 50 metres of water resistance, the FB521 handles pool laps, rain and hand washing without concern. That rating suits swimming and surface water activity, but not high-speed water sports or diving. Rinse the strap with fresh water after salt or chlorine exposure.
Warranty & Support
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