Haylou · 2021
RS4 Size, Dimensions & Wrist Fit
Case Width
37.2mm
Thickness
11.1mm
Lug-to-Lug
45.2mm
Weight
48.6g
The RS4 looks in proportion on wrists of 14–20 cm (5.5–7.9 in) round, and fills the wrist at 14.5–16.5 cm (45.2mm lug to lug).
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Does the RS4 fit your wrist?
| Wrist round (mm left each side) | 37.2mm |
|---|---|
| 14 cm / 5.5 in | Overhangs (0mm) |
| 15 cm / 5.9 in | Sweet spot (1.6mm) |
| 16 cm / 6.3 in | Sweet spot (3.2mm) |
| 17 cm / 6.7 in | Balanced (4.8mm) |
| 18 cm / 7.1 in | Balanced (6.4mm) |
| 19 cm / 7.5 in | Balanced (8mm) |
| 20 cm / 7.9 in | Balanced (9.7mm) |
The RS4 in short
- Compared with the previous RS3, it is 6.2mm narrower, 1.4mm thinner and 2.6g heavier.
- Rated for 12 days of use per charge.
- Water resistant; no depth rating published.
- 48.6g on the wrist.
- 1.78 inches LCD display.
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Size, fit and battery side by side, against any smartwatch we list.
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RS4 battery life
Published runtime
- Battery life12 days
Where it ranks among Haylou watches
- Everyday use12 days#8 of 10
- Capacity230 mAh#7 of 10
Settings to change and the 24-hour idle test are on the battery check.
2D Dimension Schematics
- Haylou RS4 37.2mm × 45.2mm · 11.1mm thick
3D preview
Haylou RS4 on a wrist
What size band does the RS4 take?
Lug width
20mm
Alternatives to the RS4
RS4 specifications
- Battery life
- 12 days
- Display
- 1.78 inches
- Resolution
- 368 x 448 px
- Water rating
- Water resistant
- Strap
- 20 mm
Show all specificationsHaylou's published specification, for reference · checked September 2026
Design
- width
- 37.2
- height
- 45.2
- volume
- 18.66 cm³
- weight
- 48.6 g
- thickness
- 11.1
- resolution
- 368 x 448 px
- screen size
- 1.78 inches
- Display type
- LCD
- Has a display
- Yes
- pixel density
- 325 ppi
- width of band
- 20 mm
- water resistance
- Water resistant
- Always-On Display
- No
- has a touch screen
- Yes
- Watch band is replaceable
- Yes
- Has sapphire glass display
- No
- Ingress Protection (IP) rating
- IP68
- has branded damage-resistant glass
- No
Battery
- battery life
- 12 days
- battery power
- 230 mAh
- has wireless charging
- Yes
- has a removable battery
- No
- Has a solar power battery
- No
- has a rechargeable battery
- Yes
Sensors
- has GPS
- No
- has a compass
- No
- Has a barometer
- No
- has a gyroscope
- No
- Has a cadence sensor
- No
- has an accelerometer
- Yes
- Monitors perspiration
- No
- Has a heart rate monitor
- Yes
- Has a temperature sensor
- No
- Monitors blood oxygenation levels
- Yes
Features
- release date
- 2021-11-11
- Has a stopwatch
- Yes
- Has smart alarm
- No
- Has call control
- No
- Has silent alarm
- Yes
- Has notifications
- Yes
- Has ECG technology
- No
- Locates your phone
- No
- has fall detection
- No
- has voice commands
- No
- Acquires GPS faster
- No
- Has vibrating alerts
- No
- Can be used to answer calls
- No
- has irregular heart rate warnings
- No
- Has a built-in camera remote control function
- No
Connectivity
- has NFC
- No
- supports ANT+
- No
- supports Wi-Fi
- No
- Bluetooth version
- 5.1
- has a cellular module
- No
- Is compatible with iOS
- Yes
- Is compatible with Android
- Yes
Miscellaneous
- Has passcode
- No
- Is compatible with Windows
- Yes
- Is compatible with Mac OS X
- No
- has an external memory slot
- No
- has a battery level indicator
- Yes
- has a socket for a 3.5 mm audio jack
- No
App & Software
- Free app
- Yes
- Has coaching
- No
- Supports routes
- No
- Has achievements
- Yes
- Has goal setting
- Yes
- Has exercise diary
- Yes
- Predicts ovulation
- Yes
- Has weight tracking
- Yes
- Predicts start date
- Yes
- Tracks water intake
- Yes
- Has inactivity alerts
- Yes
- Has period notifications
- Yes
- Has temperature tracking
- No
- Doesn’t require account
- No
- Provides activity reports
- Yes
- Displays fertile window notifications
- Yes
- Counts how many calories you've burned
- Yes
Activity tracking
- Measures pace
- No
- Tracks distance
- No
- Tracks elevation
- No
- Designed for golf
- No
- Tracks your sleep
- Yes
- Tracks steps taken
- Yes
- Designed for diving
- No
- Has a route tracker
- No
- Has exercise tagging
- Yes
- Has multi-sport mode
- No
- Tracks calorie intake
- Yes
- Provides sleep reports
- Yes
- Detects activities automatically
- Yes
- Has a stroke counter for swimming
- No
