Samsung Galaxy Watch Ultra vs Xiaomi Watch S4
Size, specs & wrist fit compared
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Which one fits you
Both need much the same wrist — roughly 50–68mm across the flat of the wrist. Neither will fit where the other won't, so decide on thickness, weight and features instead.
The Samsung Galaxy Watch Ultra and Xiaomi Watch S4 share a near-identical 47.4mm case, so wrist presence comes down to thickness, lug-to-lug and weight.
On the wrist the Xiaomi Watch S4 feels lighter (44.5g vs 60.5g, case only).
The Samsung Galaxy Watch Ultra is thinner than 86% of the 76 47mm watches we hold thickness for, the Xiaomi Watch S4 than 91% — so both wear flatter than their widths suggest.
The Samsung Galaxy Watch Ultra is 0.1mm wider, 0.1mm longer, 0.1mm thicker and 16g heavier than the Xiaomi Watch S4. Both are circular.
Samsung
Galaxy Watch Ultra
Xiaomi
Watch S4
Switch or add watches
Samsung
Galaxy Watch Ultra
Xiaomi
Watch S4
2D Dimension Schematics
Every case drawn to scale on a shared centre — from above, and in profile against the wrist.
- Samsung Galaxy Watch Ultra47.4mm · 12.1mm thick
- Xiaomi Watch S447.3mm · 12mm thick
3D preview
Samsung Galaxy Watch Ultra vs Xiaomi Watch S4 on a wrist
Sized to your own wrist, turned any way you like.
Shapes are built from published measurements, not manufacturer 3D models — accurate proportions, generic dial.
Battery life compared
Furthest apart in Smartwatch mode, where the Xiaomi Watch S4 lasts 3.8× as long as the Samsung Galaxy Watch Ultra (15 days against 4 days).
Samsung Galaxy Watch UltraXiaomi Watch S4
Smartwatch
4 days15 daysBattery Saver
100 hours—Training
48 hours—
Specifications
The short version
10 key specs| Spec | SamsungGalaxy Watch Ultra | XiaomiWatch S4 |
|---|---|---|
| Case Width | 47.4mm | 47.3mm |
| Thickness | 12.1mm | 12mm |
| Weight | 60.5g | 44.5g |
| Shape | Circular | Circular |
| Water Resistance | 10 ATM | 5 ATM |
| GPS | Yes | Yes |
| Display type | OLED/AMOLED | OLED/AMOLED |
| Screen size | 1.5 inches | 1.43 inches |
| Battery life | 4 days | 15 days |
| Released | 2024 | 2024 |
Every specification
119 specs| Spec | Samsung Galaxy Watch Ultra | Xiaomi Watch S4 |
|---|---|---|
| Design | ||
| width | 47.4 | 47.3 |
| height | 47.4 | 47.3 |
| volume | 27.19 cm³ | 26.85 cm³ |
| weight | 60.5 g | 44.5 g |
| thickness | 12.1 | 12 |
| ATM rating | 10 ATM | 5 ATM |
| resolution | 480 x 480 px | 466 x 466 px |
| screen size | 1.5 inches | 1.43 inches |
| Display type | OLED/AMOLED | OLED/AMOLED |
| Has a display | Yes | Yes |
| pixel density | 327 ppi | 326 ppi |
| maximum altitude | 29527 feet | — |
| water resistance | Waterproof | Waterproof |
| Always-On Display | Yes | Yes |
| has a touch screen | Yes | Yes |
| is designed for kids | No | No |
| waterproof depth rating | 100 m | 50 m |
| Watch band is replaceable | Yes | Yes |
| Has sapphire glass display | Yes | Yes |
| maximum operating temperature | 55 °C | — |
| Ingress Protection (IP) rating | IP68 | — |
| has branded damage-resistant glass | No | No |
| lowest potential operating temperature | -20 °C | — |
| Battery | ||
| battery life | 4 days | 15 days |
| battery power | 590 mAh | 486 mAh |
| has wireless charging | Yes | Yes |
| has a removable battery | No | No |
| Has a solar power battery | No | No |
| has a rechargeable battery | Yes | Yes |
| battery life in training mode | 48 hours | — |
| battery life in power save mode | 100 hours | — |
| Sensors | ||
| has GPS | Yes | Yes |
| has a compass | Yes | Yes |
| Has a barometer | Yes | Yes |
| has a gyroscope | Yes | Yes |
| Has a cadence sensor | No | No |
| has an accelerometer | Yes | Yes |
| Monitors perspiration | No | No |
| Has a heart rate monitor | Yes | Yes |
| Has a temperature sensor | Yes | Yes |
| Monitors blood oxygenation levels | Yes | Yes |
| Features | ||
| RAM | 2GB | — |
| release date | 2024-07-10 | 2024-10-29 |
| Has a stopwatch | Yes | Yes |
| Has smart alarm | No | No |
| Has call control | Yes | Yes |
| Has silent alarm | Yes | Yes |
| has HRV tracking | Yes | Yes |
| internal storage | 32GB | 32GB |
| measures VO2 max | Yes | Yes |
| Has notifications | Yes | Yes |
| Has ECG technology | Yes | No |
| Locates your phone | Yes | Yes |
| has a front camera | No | No |
| has fall detection | Yes | Yes |
| has voice commands | Yes | Yes |
| Acquires GPS faster | Yes | Yes |
| Has vibrating alerts | Yes | Yes |
| shows readiness level | Yes | Yes |
| Can be used to answer calls | Yes | Yes |
| measures resting heart rate | Yes | Yes |
| has irregular heart rate warnings | Yes | No |
| has fast/slow heart rate notifications | Yes | Yes |
| Has a built-in camera remote control function | Yes | Yes |
| warranty period | — | 1 years |
| number of microphones | — | 2 |
| Connectivity | ||
| has NFC | Yes | Yes |
| SIM cards | 1 eSIM | 1 eSIM |
| Wi-Fi version | Wi-Fi 4 (802.11n), Wi-Fi 5 (802.11ac) | — |
| supports ANT+ | No | No |
| supports Wi-Fi | Yes | No |
| supports Galileo | Yes | Yes |
| Bluetooth version | 5.4 | 5.3 |
| has a cellular module | Yes | Yes |
| Is compatible with iOS | No | Yes |
| Is compatible with Android | Yes | Yes |
| Miscellaneous | ||
| Has passcode | Yes | Yes |
| Has auto pause | Yes | — |
| Is compatible with Windows | No | No |
| Is compatible with Mac OS X | No | No |
| has an external memory slot | No | No |
| Compatible with smart scales | Yes | — |
| has a battery level indicator | Yes | Yes |
| has a socket for a 3.5 mm audio jack | No | No |
| Compatible with external heart rate monitors | Yes | — |
| App & Software | ||
| Ad-free | Yes | Yes |
| Free app | Yes | Yes |
| Tracks BMI | Yes | — |
| Has coaching | Yes | No |
| Includes maps | Yes | Yes |
| Supports routes | Yes | No |
| Has achievements | Yes | Yes |
| Has goal setting | Yes | Yes |
| Has exercise diary | Yes | Yes |
| Predicts ovulation | Yes | Yes |
| Can be personalised | Yes | Yes |
| Has weight tracking | Yes | Yes |
| Predicts start date | Yes | Yes |
| Tracks water intake | Yes | Yes |
| Has inactivity alerts | Yes | Yes |
| Has period notifications | Yes | Yes |
| Has temperature tracking | Yes | Yes |
| Provides activity reports | Yes | Yes |
| Displays fertile window notifications | Yes | — |
| Counts how many calories you've burned | Yes | Yes |
| Doesn’t require account | — | No |
| Activity tracking | ||
| Measures pace | Yes | Yes |
| Tracks distance | Yes | Yes |
| Tracks elevation | Yes | Yes |
| Tracks your sleep | Yes | Yes |
| Tracks steps taken | Yes | Yes |
| Designed for diving | No | No |
| Has a route tracker | Yes | Yes |
| Has exercise tagging | Yes | Yes |
| Has multi-sport mode | Yes | — |
| Tracks calorie intake | Yes | Yes |
| Provides sleep reports | Yes | Yes |
| Detects activities automatically | Yes | Yes |
| Has a stroke counter for swimming | Yes | Yes |
Wrist Fit
Samsung Galaxy Watch Ultra
Sits best on wrists ~50–68mm wide (≈ 13.4–18.2cm circumference).
Xiaomi Watch S4
Sits best on wrists ~50–68mm wide (≈ 13.4–18.2cm circumference).
Frequently Asked Questions
Is the Samsung Galaxy Watch Ultra bigger than the Xiaomi Watch S4?
The Samsung Galaxy Watch Ultra is bigger — 47.4mm vs 47.3mm case width.
Which fits a smaller wrist better, the Samsung Galaxy Watch Ultra or the Xiaomi Watch S4?
The Samsung Galaxy Watch Ultra suits wrists around 50–68mm wide, and the Xiaomi Watch S4 around 50–68mm. The one with the smaller lower bound is the safer pick for a small wrist.
Can I see the Samsung Galaxy Watch Ultra and Xiaomi Watch S4 side by side at true scale?
Yes — the schematics and photos above show both watches at matched scale, and our fit tool overlays each on your wrist width.