Fitbit · 2020
SenseSize, Dimensions & Wrist Fit
The Fitbit Sense sits best on flat wrist widths of about 43–58mm (≈ 11.5–15.5cm wrist circumference). Adjust the slider below to check your wrist.
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The Sense in short
The figures that decide whether this watch suits you, pulled out of the full specification sheet further down.
- Between 12 hours and 6 days per charge depending on the power mode — smartwatch at best, gps at worst.
- Water rated to 50 m.
- 48.2g on the wrist. Heavier than 88% of the 40mm watches we have weights for.
- 1.58 inches OLED/AMOLED display, always-on capable.
- Takes 20mm bands, so third-party straps fit without an adapter.
Does the Sense fit your wrist?
Drag the slider to your wrist width and see the Sense overlaid at true scale. Lug-to-lug — not case diameter — decides whether a watch overhangs your wrist.
Watch Fit Tool
For sports watches, lug-to-lug (L2L) is what matters most — it decides whether a watch overhangs your wrist. Bulky is fine; overhang is not.
Measure at the point where you wear your watch — typically just below the wrist bone.
Flat width — lay your arm on a table, palm facing up, and measure straight across the top of your wrist with a ruler. Bone to bone; do not follow the curve down the sides.
Around — wrap a tape measure snugly round the wrist. No tape? Wrap a strip of paper, mark the overlap and hold the strip against a ruler.
Width ≠ circumference. They are different numbers — around 170mm is about 64mm across — so set the toggle to whichever one you actually measured before you type it in.
Fitbit Sense
Case 40.4mm · Lug-to-lug 40.4mm · Thickness 12.4mm · 48g
Balanced Fit
40.4mm on a 55mm wrist
Comfortably inside the edges of your wrist, and it seats and sits low enough to wear without thinking about it.
On a 55mm wrist the sweet spot is 47–53mm lug to lug. This one is 40.4mm, so you could go bigger.
Measure where you wear it, just below the wrist bone. Either of these works — the tool converts between them.
- 1. Flat width — arm flat on a table, palm up. Measure straight across the top of the wrist, bone to bone, ignoring the curve down the sides.
- 2. Around — a tape, or a strip of paper marked and held against a ruler, snug the whole way round.
Leather: Attaches at the lugs, so the case back rests on your skin. Thins and softens with wear. Typical figures, not this model’s own.
Show the measurementsHide the measurements
- Across the wrist7.3mm spare each side
Comfortable, with visible skin either side.
- Off the wrist12.4mm off the skin
Normal sports-watch height for a wrist this size. (12.4mm case, back against the skin)
- How it seats~3.5mm under the rim
Seats well, with the case back following most of the wrist.
- Weight on the wrist48g
Light enough to forget you have it on. (0.9g per mm of wrist)
Happy with the fit? Check current availability for the Sense.
Check offer2D Dimension Schematics
The Sense drawn to scale — from above, and in profile against the wrist.
- Fitbit Sense40.4mm · 12.4mm thick
3D preview
Fitbit Sense on a wrist
On an arm sized to your own wrist — the view a product photo never gives you.
Shapes are built from published measurements, not manufacturer 3D models — accurate proportions, generic dial.
How long the Sense lasts, by power mode
Runtime changes by a factor of 12 depending on what you leave switched on. Bars are scaled against the longest mode.
- Smartwatch6 days
- GPS12 hours
How the Sense ranks on battery
Against the 10 Fitbit watches in our database, ranked on each figure Fitbit publishes.
- Everyday use6 days#2 of 10
Top three in the Fitbit range for everyday (smartwatch) use.
What size band does the Sense take?
Lug width
20mm
Any 20mm strap fits, so you are not restricted to Fitbit's own bands. Quick-release pins let you swap without tools — check that a replacement lists 20mm and quick-release before buying.
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Sense specifications
The figures that decide a purchase, followed by every line Fitbit publishes.
- Battery life
- 6 days
- Display
- 1.58 inches
- Resolution
- 336 x 336 px
- Water rating
- 5 ATM
- Glass
- Gorilla Glass 3
- Strap
- 20 mm
- Storage
- 4GB
- Charging
- 2 hours
Full specification sheet
111 published lines across 8 groups, unedited
Design
- width
- 40.4
- height
- 40.4
- volume
- 20.24 cm³
- weight
- 48.2 g
- thickness
- 12.4
- ATM rating
- 5 ATM
- resolution
- 336 x 336 px
- screen size
- 1.58 inches
- Display type
- OLED/AMOLED
- Has a display
- pixel density
- 301 ppi
- width of band
- 20 mm
- maximum altitude
- 28000 feet
- water resistance
- Waterproof
- Always-On Display
- has a touch screen
- Gorilla Glass version
- Gorilla Glass 3
- waterproof depth rating
- 50 m
- Watch band is replaceable
- Has sapphire glass display
- maximum operating temperature
- 45 °C
- Ingress Protection (IP) rating
- IP68
- has branded damage-resistant glass
- lowest potential operating temperature
- -10 °C
Battery
- charge time
- 2 hours
- battery life
- 6 days
- battery power
- 266 mAh
- has wireless charging
- has a removable battery
- battery life with GPS on
- 12 hours
- Has a solar power battery
- has a rechargeable battery
Sensors
- has GPS
- has a compass
- Has a barometer
- has a gyroscope
- Has a cadence sensor
- has an accelerometer
- Monitors perspiration
- Has a heart rate monitor
- Has a temperature sensor
- Monitors blood oxygenation levels
Features
- release date
- 2020-08-25
- Has a stopwatch
- Has smart alarm
- warranty period
- 1 years
- Has call control
- Has silent alarm
- has HRV tracking
- internal storage
- 4GB
- Has notifications
- Has ECG technology
- Locates your phone
- has fall detection
- has voice commands
- Acquires GPS faster
- Has vibrating alerts
- number of microphones
- 1
- shows readiness level
- Can be used to answer calls
- measures resting heart rate
- has irregular heart rate warnings
- has fast/slow heart rate notifications
- Has a built-in camera remote control function
Connectivity
- has NFC
- Wi-Fi version
- Wi-Fi 4 (802.11n)
- supports ANT+
- supports Wi-Fi
- Bluetooth version
- 5
- has a cellular module
- Is compatible with iOS
- Is compatible with Android
Miscellaneous
- Has passcode
- Has auto pause
- Is compatible with Windows
- Is compatible with Mac OS X
- has an external memory slot
- Compatible with smart scales
- has a battery level indicator
- has a socket for a 3.5 mm audio jack
- Compatible with external heart rate monitors
App & Software
- Ad-free
- Free app
- Has achievements
- Has goal setting
- Has exercise diary
- Predicts ovulation
- Can be personalised
- Has weight tracking
- Predicts start date
- Tracks water intake
- number of exercises
- 20
- Has inactivity alerts
- Has period notifications
- Has temperature tracking
- Provides activity reports
- Counts how many calories you've burned
Activity tracking
- Measures pace
- Tracks distance
- Tracks elevation
- Designed for golf
- Tracks your sleep
- Tracks steps taken
- Designed for diving
- Has a route tracker
- Has exercise tagging
- Has multi-sport mode
- Tracks calorie intake
- Provides sleep reports
- Detects activities automatically
- Has a stroke counter for swimming
Alternatives to the Sense
Watches that cover a similar amount of wrist, with the measurements that separate them.
Sense — Frequently Asked Questions
Will the Fitbit Sense fit my wrist?
The Fitbit Sense looks balanced on flat wrist widths of roughly 43–58mm (about 11.5–15.5cm circumference). Drag the slider above to check it against your own measurement.
What size band does the Fitbit Sense take?
20mm. Any 20mm strap fits, so you are not limited to Fitbit's own bands — look for a quick-release fitting if you want to swap without tools.
How long does the Fitbit Sense battery last?
Between 12 hours and 6 days per charge, depending on the power mode. Fitbit rates Smartwatch at 6 days and GPS at 12 hours; the chart above lists all 2 modes.
How does the Fitbit Sense battery compare with other Fitbit watches?
At 6 days in everyday use it ranks #2 of the 10 Fitbit watches in our database — the top 20% of the range. The full ranking, including GPS and power-saving figures, is on our Fitbit battery life comparison.
Is the Fitbit Sense thick for a 40mm watch?
At 12.4mm, thicker than 84% of 40mm watches — it will sit noticeably high on the wrist. Thickness, not case width, is what decides whether a watch catches on a shirt cuff.
What other watches are the same size as the Fitbit Sense?
TAG Heuer Aquaracer Professional 200 Solargraph 40 UK Limited Edition, Xiaomi Redmi Watch 6, Vivo Watch GT 2 - Bluetooth, Samsung Galaxy Watch8 - LTE · 40mm all sit within half a millimetre of the Fitbit Sense's 40.4mm case, so they cover the same amount of wrist.
