Apple Watch Ultra 3 vs Xiaomi Watch S4 Sport
Size, specs & wrist fit compared
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Which one fits you
On wrists narrower than about 52mm, the Xiaomi Watch S4 Sport is the safer pick — it stays proportionate down to roughly 49mm, where the Apple Watch Ultra 3 starts to hang over the edge. Above 52mm both sit cleanly, and the Apple Watch Ultra 3 gives you more presence.
The Xiaomi Watch S4 Sport wears larger than the Apple Watch Ultra 3 (46.9mm vs 44mm case), giving it more wrist presence — and needing a wider wrist to sit cleanly.
The Apple Watch Ultra 3 is the slimmer of the two (12mm vs 12.6mm), so it slides under a cuff more easily.
On the wrist the Xiaomi Watch S4 Sport feels lighter (49g vs 61.8g, case only).
Among the 326 44mm watches we hold thickness for, the Apple Watch Ultra 3 is thinner than 89%, so it wears flatter than its width suggests.
The Xiaomi Watch S4 Sport is middle-of-the-pack for thickness among the 108 47mm watches in the database.
The Xiaomi Watch S4 Sport is 2.9mm wider, 2.1mm shorter, 0.6mm thicker and 12.8g lighter than the Apple Watch Ultra 3.
Apple
Watch Ultra 3
Xiaomi
Watch S4 Sport
Switch or add watches
Apple
Watch Ultra 3
Xiaomi
Watch S4 Sport
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.
Apple Watch Ultra 3
Case 49.0mm · Lug-to-lug 49.0mm · Thickness 12.0mm · 62g
Sweet Spot
49mm on a 55mm wrist
Across the wrist it works — 3.0mm spare each side — but wide enough that the edge of the case back lifts clear of the skin.
On a 55mm wrist the sweet spot is 47–53mm lug to lug. This one is 49mm.
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 wrist3.0mm spare each side
Fills the wrist without reaching the edge.
- Off the wrist12.0mm off the skin
Normal sports-watch height for a wrist this size. (12.0mm case, back against the skin)
- How it seats~7.3mm under the rim
Wide enough that the edge of the case back lifts clear of the skin.
- Weight on the wrist62g
Substantial without being a burden — the usual weight of a steel watch on a wrist this size. (1.1g per mm of wrist)
Xiaomi Watch S4 Sport
Case 46.9mm · Lug-to-lug 46.9mm · Thickness 12.6mm · 49g
Sweet Spot
46.9mm on a 55mm wrist
Across the wrist it works — 4.1mm spare each side — but wide enough that the edge of the case back lifts clear of the skin.
On a 55mm wrist the sweet spot is 47–53mm lug to lug. This one is 46.9mm, 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 wrist4.1mm spare each side
Fills the wrist without reaching the edge.
- Off the wrist12.6mm off the skin
Normal sports-watch height for a wrist this size. (12.6mm case, back against the skin)
- How it seats~6.1mm under the rim
Wide enough that the edge of the case back lifts clear of the skin.
- Weight on the wrist49g
Light enough to forget you have it on. (0.9g per mm of wrist)
2D Dimension Schematics
Every case drawn to scale on a shared centre — from above, and in profile against the wrist.
- Apple Watch Ultra 344mm × 49mm · 12mm thick
- Xiaomi Watch S4 Sport46.9mm · 12.6mm thick
3D preview
Apple Watch Ultra 3 vs Xiaomi Watch S4 Sport 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 Sport lasts 8.6× as long as the Apple Watch Ultra 3 (15 days against 42 hours).
Apple Watch Ultra 3Xiaomi Watch S4 Sport
Smartwatch
1.75 days15 daysBattery Saver
72 hours—
Specifications
The short version
11 key specs| Spec | AppleWatch Ultra 3 | XiaomiWatch S4 Sport |
|---|---|---|
| Case Width | 44mm | 46.9mm |
| Lug-to-Lug | 49mm | 46.9mm |
| Thickness | 12mm | 12.6mm |
| Weight | 61.8g | 49g |
| Shape | Rectangle | Circular |
| Water Resistance | 10 ATM | 5 ATM |
| GPS | Yes | Yes |
| Display type | OLED/AMOLED | OLED/AMOLED |
| Screen size | 1.98 inches | 1.43 inches |
| Battery life | 1.75 days | 15 days |
| Released | 2025 | 2024 |
Every specification
121 specs| Spec | Apple Watch Ultra 3 | Xiaomi Watch S4 Sport |
|---|---|---|
| Design | ||
| width | 44 | 46.9 |
| height | 49 | 46.9 |
| volume | 25.87 cm³ | 27.72 cm³ |
| weight | 61.8 g | 49 g |
| thickness | 12 | 12.6 |
| ATM rating | 10 ATM | 5 ATM |
| resolution | 422 x 514 px | 466 x 466 px |
| screen size | 1.98 inches | 1.43 inches |
| Display type | OLED/AMOLED | OLED/AMOLED |
| Has a display | Yes | Yes |
| pixel density | 326 ppi | 326 ppi |
| 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 | 40 m |
| Watch band is replaceable | Yes | Yes |
| Has sapphire glass display | Yes | Yes |
| maximum operating temperature | 55 °C | — |
| Ingress Protection (IP) rating | IPX6 | — |
| has branded damage-resistant glass | No | No |
| lowest potential operating temperature | -20 °C | — |
| width of band | — | 22 mm |
| Battery | ||
| charge time | 1.5 hours | — |
| battery life | 1.75 days | 15 days |
| 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 power save mode | 72 hours | — |
| battery power | — | 586 mAh |
| 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 | 2025-09-09 | 2024-07-19 |
| Has a stopwatch | Yes | Yes |
| Has smart alarm | No | No |
| warranty period | 1 years | 1 years |
| Has call control | Yes | Yes |
| Has silent alarm | Yes | Yes |
| has HRV tracking | Yes | Yes |
| internal storage | 64GB | 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 | No |
| has voice commands | Yes | Yes |
| Acquires GPS faster | Yes | Yes |
| Has vibrating alerts | Yes | Yes |
| number of microphones | 1 | 1 |
| 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 |
| shows readiness level | — | Yes |
| Connectivity | ||
| has NFC | Yes | Yes |
| SIM cards | 1 eSIM | 1 eSIM |
| Wi-Fi version | Wi-Fi 4 (802.11n) | — |
| supports ANT+ | No | No |
| supports Wi-Fi | Yes | No |
| supports Galileo | Yes | Yes |
| Bluetooth version | 5.3 | 5.2 |
| has a cellular module | Yes | Yes |
| Is compatible with iOS | Yes | Yes |
| Is compatible with Android | No | Yes |
| Miscellaneous | ||
| has aptX | No | — |
| Has passcode | Yes | Yes |
| Has auto pause | Yes | — |
| has crash detection | 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 |
| Has coaching | No | 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 |
| Designed for golf | No | — |
| Tracks your sleep | Yes | Yes |
| Tracks steps taken | Yes | Yes |
| Designed for diving | Yes | Yes |
| Has a route tracker | Yes | Yes |
| Has exercise tagging | Yes | Yes |
| Has multi-sport mode | Yes | — |
| Tracks calorie intake | No | Yes |
| Provides sleep reports | Yes | Yes |
| Detects activities automatically | Yes | Yes |
| Has a stroke counter for swimming | Yes | Yes |
Wrist Fit
Apple Watch Ultra 3
Sits best on wrists ~52–70mm wide (≈ 13.9–18.7cm circumference).
Xiaomi Watch S4 Sport
Sits best on wrists ~49–67mm wide (≈ 13.1–17.9cm circumference).
Frequently Asked Questions
Is the Apple Watch Ultra 3 bigger than the Xiaomi Watch S4 Sport?
The Xiaomi Watch S4 Sport is bigger — 46.9mm vs 44mm case width.
Which fits a smaller wrist better, the Apple Watch Ultra 3 or the Xiaomi Watch S4 Sport?
The Apple Watch Ultra 3 suits wrists around 52–70mm wide, and the Xiaomi Watch S4 Sport around 49–67mm. The one with the smaller lower bound is the safer pick for a small wrist.
Can I see the Apple Watch Ultra 3 and Xiaomi Watch S4 Sport 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.