Between the Galaxy Watch Ultra 2 and Watch S4, the Galaxy Watch Ultra 2 comes out ahead in peak brightness and water resistance, while the Watch S4 wins on battery life and weight. Overall, the Galaxy Watch Ultra 2 scores 50.8 and the Watch S4 scores 63.9 on our Mars Score.
Which should you buy?
The Watch S4 is the clear pick on raw spec strength, leading by 13.1 points on the Mars Score. The margin is wide enough that the underdog only makes sense if its individual strengths line up with what you specifically need.
Pick the Galaxy Watch Ultra 2 if the display is what you stare at all day — refresh rate, brightness, or sharpness is where the difference will be most visible. The biggest gaps in its favor are peak brightness, water resistance, display size.
Pick the Watch S4 if your top frustration with your current device is running out of charge before the day ends — endurance is the lead spec here. Its strongest claims are battery life, weight.
Both ship with comparable ecg, cellular, spo2, so those specs don't separate the two — focus on the differences below.
Bottom line: the Watch S4 is the safer default. The other model is the right choice only when its specific advantages line up with your priorities.
Why Samsung - Galaxy Watch Ultra 2 wins
- ▲Peak brightness — 36.36% more. 3000 nits vs 2200 nits.
- ▲Water resistance — 5.00 ATM more. 10 vs 5.
- ▲Display size — 4.90% more. 1.5 " vs 1.43 ".
Why Xiaomi - Watch S4 wins
- ▲Battery life — 500.00% more. 360 h vs 60 h.
- ▲Weight — 16.00 g less. 44 vs 60.
Spec comparison
Design
| Spec | Samsung - Galaxy Watch Ultra 2 | Xiaomi - Watch S4 |
|---|---|---|
| Case size | 47 mm | 47 mm |
| Weight | 60 g | 44 glead |
| Case material | titanium | stainless steel |
| Water resistanceⓘ | 10 ATMlead | 5 ATM |
Display
| Spec | Samsung - Galaxy Watch Ultra 2 | Xiaomi - Watch S4 |
|---|---|---|
| Display size | 1.5 "lead | 1.43 " |
| Always-on display | true | true |
| Peak brightnessⓘ | 3000 nitslead | 2200 nits |
Health & Fitness
| Spec | Samsung - Galaxy Watch Ultra 2 | Xiaomi - Watch S4 |
|---|---|---|
| ECG | true | true |
| SpO2 | true | true |
| Temperature sensor | true | true |
| Sleep tracking | true | true |
| Blood pressure | truelead | false |
Battery & Connectivity
| Spec | Samsung - Galaxy Watch Ultra 2 | Xiaomi - Watch S4 |
|---|---|---|
| Battery life | 60 h | 360 hlead |
| GPS | true | true |
| Cellular | true | true |
| NFC | true | true |
| OS | WearOS | HyperOSlead |
Frequently asked
Which has longer battery life, Galaxy Watch Ultra 2 or Watch S4?+
Watch S4 lasts 360h vs 60h.
Do Galaxy Watch Ultra 2 or Watch S4 support ECG?+
Both support ECG.
Which has cellular, Galaxy Watch Ultra 2 or Watch S4?+
Both offer cellular variants.
Spec-level deep dives
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